Earnings Per Common Share (Schedule of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Basic earnings allocated to common shareholders									$ 97,577	$ 80,637	$ 59,398
Net income	$ 26,740	$ 25,780	$ 21,946	$ 24,361	$ 18,920	$ 21,583	$ 21,227	$ 19,844	98,827	81,574	60,016
Earnings allocated to participating securities - preferred shares									175	157	95
Earnings allocated to participating securities - nonvested restricted shares									$ 1,075	$ 780	$ 523
Weighted average common shares outstanding									57,019	52,618	47,993
Basic earnings per common share	$ 0.46	$ 0.45	$ 0.38	$ 0.42	$ 0.34	$ 0.41	$ 0.40	$ 0.38	$ 1.71	$ 1.53	$ 1.24
Earnings allocated to common shareholders, Diluted									$ 97,577	$ 80,640	$ 59,407
Weighted average number of common shares outstanding									57,019	52,618	47,993
Dilutive effect of equity awards and warrants									13	565	1,058
Weighted average diluted common shares outstanding									57,032	53,183	49,051
Diluted earnings per common share	$ 0.46	$ 0.45	$ 0.38	$ 0.42	$ 0.34	$ 0.41	$ 0.40	$ 0.37	$ 1.71	$ 1.52	$ 1.21
Potentially dilutive share options that were not included in the computation of diluted EPS because to do so would be anti-dilutive.									37	64	64