Earnings Per Common Share (Schedule of Basic and Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Basic earnings allocated to common shareholders									$ 80,637	$ 59,398	$ 45,700
Net income (loss)	18,920	21,583	21,227	19,844	19,973	13,276	14,591	12,176	81,574	60,016	46,143
Earnings allocated to participating securities - preferred shares									157	95	0
Earnings allocated to participating securities - nonvested restricted shares									780	523	443
Weighted average common shares outstanding									52,618	47,993	39,260
Earnings (loss) basic (dollars per share)	$ 0.34	$ 0.41	$ 0.40	$ 0.38	$ 0.39	$ 0.26	$ 0.28	$ 0.31	$ 1.53	$ 1.24	$ 1.16
Earnings allocated to common shareholders, Diluted									$ 80,640	$ 59,407	$ 45,700
Weighted average number of common shares outstanding									52,618	47,993	39,260
Dilutive effect of equity awards and warrants									565	1,058	3
Weighted average diluted common shares outstanding									53,183	49,051	39,263
Earnings (loss) diluted (dollars per share)	$ 0.34	$ 0.41	$ 0.40	$ 0.37	$ 0.38	$ 0.25	$ 0.28	$ 0.31	$ 1.52	$ 1.21	$ 1.16
Potentially dilutive share options that were not included in the computation of diluted EPS because to do so would be anti-dilutive.									64	64	9