Earnings per Common Share Computation of Basic and Diluted Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Net income	$ 86,136	$ 58,224	$ 44,546
Preferred stock dividends	0	3,300	3,422
Net income available to common shareholders	$ 86,136	$ 54,924	$ 41,124
Weighted Average Number of Shares Outstanding, Basic and Diluted [Abstract]
Weighted average common shares outstanding for basic earnings per share computation	43,566,681	42,965,987	42,749,526
Dilutive effect of stock-based compensation	477,921	126,991	97,670
Weighted average common shares outstanding for diluted earnings per common share computation	44,044,602	43,092,978	42,847,196
Earnings Per Share, Basic and Diluted [Abstract]
Basic earnings per common share (in dollars per share)	$ 1.98	$ 1.28	$ 0.96
Diluted earnings per common share (in dollars per share)	$ 1.96	$ 1.27	$ 0.96
Stock Options
Earnings Per Share, Basic and Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	21,372	2,427,823	2,865,832
Unvested Restricted Stock
Earnings Per Share, Basic and Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	37,734	41,240	9,427