Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net Income		$ 21,946	$ 21,227	$ 46,307	$ 41,071
Earnings allocated to participating securities - nonvested restricted shares		248	206	475	378
Earnings allocated to participating securities - preferred shares		39	41	82	79
Earnings allocated to common shareholders, Basic		$ 21,659	$ 20,980	$ 45,750	$ 40,614
Weighted average common shares outstanding		57,055	52,088	56,999	51,600
Basic earnings per common share		$ 0.38	$ 0.40	$ 0.80	$ 0.79
Dilutive effect of equity awards and warrants		14	406	13	863
Earnings allocated to common shareholders, Diluted	[1]	$ 21,659	$ 20,981	$ 45,750	$ 40,617
Weighted average diluted common shares outstanding		57,069	52,494	57,012	52,463
Diluted earnings per common share		$ 0.38	$ 0.40	$ 0.80	$ 0.77
Potentially dilutive share options that were not included in the computation of diluted EPS because to do so would be anti-dilutive.		37	63	45	73

[1] Earnings allocated to common shareholders for basic and diluted EPS may differ under the two-class method as a result of adding common stock equivalents for options and warrants to dilutive shares outstanding, which alters the ratio used to allocate earnings to common shareholders and participating securities for the purposes of calculating diluted EPS.