Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net income	$ 71,529	$ 88,075	$ 95,916
Preferred stock dividends	(8,775)	(8,775)	(8,775)
Net income available to common shareholders	62,754	79,300	87,141
Income allocated to participating securities	(566)	(726)	(973)
Net income allocated to common shareholders	$ 62,188	$ 78,574	$ 86,168
Basic weighted average common shares outstanding (in shares)	100,388,802	99,612,473	98,384,443
Dilutive effect of stock options and restricted stock units (in shares)	0	357,365	0
Diluted weighted average common shares outstanding (in shares)	100,388,802	99,969,838	98,384,443
Basic EPS (in dollars per share)	$ 0.62	$ 0.79	$ 0.88
Diluted EPS (in dollars per share)	$ 0.62	$ 0.79	$ 0.88
Employee Non Employee Director Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earnings per share (in shares)	6,247	14,167	962,783
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earnings per share (in shares)	740,093	644,319	758,792