Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Equity - Narrative (Details)

Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended	115 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2016	Nov. 07, 2016	Oct. 31, 2016	Oct. 26, 2016	May 18, 2016	Dec. 31, 2015	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)									5,000,000
Repurchase and retirement of common stock (in shares)	1,597,126	4,693,037	16,962,604
Shares repurchased, value	$ 3,800	$ 11,515	$ 43,496
Shares available for purchase (in shares)	537,396	537,396	537,396
Shares surrendered for tax withholdings (in shares)		901,691
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)	17,407	69,835
Unrecognized compensation cost for stock based compensation	$ 4,984	$ 4,984	$ 4,984
Unrecognized compensation cost for stock based compensation, period of recognition		2 years 1 month 13 days
Purchase of shares (in shares)	3,797,272	7,356,887
Intrinsic value of options exercised	$ 5,426	$ 10,210
Options \| Awards Granted in 2016
Capital Unit [Line Items]
Unrecognized compensation cost for stock based compensation	1,060	$ 1,060	1,060
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	5,006	$ 5,006	5,006
Unrecognized compensation cost for stock based compensation, period of recognition		2 years 8 months 18 days
Restricted stock forfeited (in shares)		10,000
Restricted shares \| Employees
Capital Unit [Line Items]
Non-cash compensation expense	1,286	$ 3,964
Restricted shares \| Consultants and Independent Financial Advisors
Capital Unit [Line Items]
Non-cash compensation expense	14	32
Restricted shares \| Awards Granted in 2016
Capital Unit [Line Items]
Unrecognized compensation cost for stock based compensation	$ 2,358	$ 2,358	$ 2,358
Unrecognized compensation cost for stock based compensation, period of recognition		3 years 3 months
Options, Warrants, and Other
Capital Unit [Line Items]
Shares surrendered for tax withholdings (in shares)	1,588,988	2,865,263
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
At the market shares sold (in shares)	789,468	1,161,895
Proceeds from issuance of public offering	$ 19,266	$ 28,303
Offering expenses	422	682
Dividends paid	$ 7,780	$ 22,514
Dividends paid per share on monthly basis (in USD per share)		$ 0.1667
Subsequent Event
Capital Unit [Line Items]
Shares authorized for repurchase (in shares) (up to)				10,000,000	10,000,000
Number of securities purchased by conversion of warrant (in shares)						10,699,999