Basis of Presentation (Details 4) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reconciliation of basic earnings per share ("EPS") to diluted EPS
Net income available to common stockholders	$ 20,614	$ 7,668	$ 20,006	$ 53,151	$ 43,303
Basic weighted-average shares outstanding	49,010		48,377	48,972	48,482
Dilutive effect of potential common stock equivalents — stock options and restricted stock units	217		174	200	121
Diluted weighted-average shares outstanding	49,227		48,551	49,172	48,603
Earnings per common share:
Basic (in dollars per share)	$ 0.42		$ 0.41	$ 1.09	$ 0.89
Diluted (in dollars per share)	$ 0.42		$ 0.41	$ 1.08	$ 0.89
Potentially dilutive securities excluded from earnings per diluted share because their effect is anti-dilutive	0		0	0	0