Intangible Assets (Intangible Assets Subject To Amortization) (Detail)

Intangible Assets (Intangible Assets Subject To Amortization) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	10 years 1 month 28 days
Gross Carrying Amount	$ 205,160	$ 174,259
Accumulated Amortization	56,368	51,258
Technology
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	25,563	23,483
Accumulated Amortization	10,039	9,223
Technology \| Minimum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	1 year
Technology \| Maximum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	7 years 8 months 12 days
Relationships With Financial Advisors
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	108,092	81,438
Accumulated Amortization	25,748	23,704
Relationships With Financial Advisors \| Minimum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	9 years 2 months 12 days
Relationships With Financial Advisors \| Maximum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	20 years
Relationships With Financial Advisors \| Weighted Average
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	10 years 2 months 12 days
Vendor Relationship
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	7 years
Gross Carrying Amount	3,613	3,613
Accumulated Amortization	3,520	3,458
Covenants Not-to-Compete
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	5,812	5,401
Accumulated Amortization	2,404	2,100
Covenants Not-to-Compete \| Minimum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	2 years 2 months 12 days
Covenants Not-to-Compete \| Maximum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	5 years
Covenants Not-to-Compete \| Weighted Average
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	3 years
Customer Account
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	2,029	2,029
Accumulated Amortization	1,578	1,516
Customer Account \| Minimum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	6 years 10 months 24 days
Customer Account \| Maximum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	10 years
Renewal revenue
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	7 years 9 months 18 days
Gross Carrying Amount	39,503	39,503
Accumulated Amortization	3,358	2,099
Trade names
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	16,910	15,154
Accumulated Amortization	6,120	5,563
Trade names \| Minimum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	7 years 2 months 12 days
Trade names \| Maximum
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	10 years
Trade names \| Weighted Average
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	9 years
Relationships With Investment Banking Clients
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	4 years
Gross Carrying Amount	2,586	2,586
Accumulated Amortization	2,586	2,586
Leases
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	6 years 4 months 24 days
Gross Carrying Amount	861	861
Accumulated Amortization	861	861
Referral Agreement
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	6 years 7 months 6 days
Gross Carrying Amount	124	124
Accumulated Amortization	87	81
Other
Indefinite-lived Intangible Assets [Line Items]
Estimated useful life	6 years
Gross Carrying Amount	67	67
Accumulated Amortization	$ 67	$ 67

Quarterly report pursuant to Section 13 or 15(d)

Intangible Assets (Intangible Assets Subject To Amortization) (Detail)