Earnings Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Common Share
Net income	$ 22,300	$ 15,665	$ 53,849	$ 29,517
Preferred stock dividends	(2,194)	(2,827)	(4,388)	(2,827)
Net income available to common shareholders	20,106	12,838	49,461	26,690
Income allocated to participating securities	(232)	(154)	(552)	(314)
Net income allocated to common shareholders	$ 19,874	$ 12,684	$ 48,909	$ 26,376
Basic weighted average common shares outstanding	98,275,886	97,021,334	98,191,434	96,848,989
Diluted weighted average common shares outstanding	98,275,886	97,021,334	98,191,434	96,848,989
Basic EPS (in dollars per share)	$ 0.20	$ 0.13	$ 0.50	$ 0.27
Diluted EPS (in dollars per share)	$ 0.20	$ 0.13	$ 0.50	$ 0.27
Antidilutive securities excluded from computation of earnings per share
Restricted stock units excluded from the computation of earnings per share (in shares)	803,318	421,752	731,973	361,152
Options
Antidilutive securities excluded from computation of earnings per share
Stock options excluded from computation of earnings per share (in shares)	1,011,219	1,949,670	1,030,651	2,387,763