Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Equity - Narrative (Details)

Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		112 Months Ended
	Jul. 30, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	May 18, 2016	Dec. 31, 2015	Nov. 30, 2014	Oct. 31, 2011	Mar. 31, 2007
Capital Unit [Line Items]
Shares authorized for repurchase (in shares) (up to)											2,500,000
Shares authorized for additional repurchase (in shares)									10,000,000	5,000,000
Repurchase and retirement of common stock (in shares)		1,572,519		3,095,911		15,365,478
Shares repurchased, value		$ 4,053		$ 7,716		$ 39,696
Shares available for purchase (in shares)		2,134,522		2,134,522		2,134,522
Shares tendered in payment of exercise price and taxes (in shares)				1,198,443
Non-cash compensation expense		$ 1,341	$ 2,424	$ 2,696	$ 5,684
Shares surrendered for tax withholdings (in shares)				548,305
Preferred stock, shares authorized (in shares)		50,000,000		50,000,000		50,000,000	50,000,000	25,000,000
Common stock, shares authorized (in shares)		1,000,000,000		1,000,000,000		1,000,000,000	1,000,000,000	800,000,000
Options
Capital Unit [Line Items]
Options forfeited (in shares)				52,428
Unrecognized compensation cost for stock based compensation		$ 11,334		$ 11,334		$ 11,334
Unrecognized compensation cost for stock based compensation, period of recognition				2 years 4 months 13 days
Purchase of shares (in shares)		2,255,076		3,559,615
Intrinsic value of options exercised		$ 3,067		$ 4,784
Options \| Awards Granted in 2016
Capital Unit [Line Items]
Unrecognized compensation cost for stock based compensation		1,289		$ 1,289		1,289
Unrecognized compensation cost for stock based compensation, period of recognition				2 years 8 months 2 days
Restricted shares
Capital Unit [Line Items]
Unrecognized compensation cost for stock based compensation		$ 5,465		$ 5,465		5,465
Unrecognized compensation cost for stock based compensation, period of recognition				2 years 11 months 16 days
Restricted stock forfeited (in shares)		10,000		10,000
Restricted shares \| Employees
Capital Unit [Line Items]
Non-cash compensation expense		$ 1,326		$ 2,678
Restricted shares \| Consultants and Independent Financial Advisors
Capital Unit [Line Items]
Non-cash compensation expense		15		18
Restricted shares \| Awards Granted in 2016
Capital Unit [Line Items]
Unrecognized compensation cost for stock based compensation		$ 2,529		$ 2,529		$ 2,529
Unrecognized compensation cost for stock based compensation, period of recognition				3 years 6 months
Options, Warrants, and Other [Member]
Capital Unit [Line Items]
Shares surrendered for tax withholdings (in shares)		1,232,496		1,276,275
Series A Preferred Stock
Capital Unit [Line Items]
Preferred stock, shares authorized (in shares)		17,290,000		17,290,000		17,290,000		17,290,000
Proceeds from issuance of public offering		$ 8,796		$ 9,037
At the market shares sold (in shares)		362,427		372,427
Offering expenses		$ 219		$ 260
Dividends paid		$ 7,389		$ 14,734
Dividends paid per share on monthly basis (in USD per share)				$ 0.1667
Subsequent Event \| Series A Preferred Stock
Capital Unit [Line Items]
Proceeds from issuance of public offering	$ 10,282
At the market shares sold (in shares)	422,683
Offering expenses	$ 206