Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basic EPS [Abstract]
Weighted average common shares, Basic (in shares)	43,923,000	33,191,000	40,187,000	33,128,000
Net income available to common shareholders	$ 16,916	$ 13,257	$ 24,565	$ 26,907
Basic EPS (in dollars per share)	$ 0.39	$ 0.40	$ 0.61	$ 0.81
Diluted EPS [Abstract]
Weighted average common shares, Diluted (in shares)	43,923,000	33,191,000	40,187,000	33,128,000
Dilutive effect of common stock option and restricted stock (in shares)	393,000	301,000	388,000	325,000
Weighted average common shares and common share equivalent (in shares)	44,316,000	33,492,000	40,575,000	33,453,000
Net income available to common shareholders	$ 16,916	$ 13,257	$ 24,565	$ 26,907
Diluted EPS (in dollars per share)	$ 0.38	$ 0.40	$ 0.61	$ 0.80
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options excluded from calculation of diluted EPS (in shares)	1,231,395	1,271,116	1,203,046	1,209,201