Reconciliation of BEPS - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reconciliation of basic earnings per share ("EPS") to diluted EPS
Net income available to common stockholders	$ 21,595	$ 10,380	$ 20,614	$ 53,156	$ 53,151
Basic weighted-average shares outstanding	48,998		49,010	49,157	48,972
Dilutive effect of potential common stock equivalents — stock options and restricted stock units	241		217	220	200
Diluted weighted-average shares outstanding	49,239		49,227	49,377	49,172
Earnings per common share:
Basic (in USD per share)	$ 0.44		$ 0.42	$ 1.08	$ 1.09
Diluted (in USD per share)	$ 0.44		$ 0.42	$ 1.08	$ 1.08
Potentially dilutive securities excluded from earnings per diluted share because their effect is anti-dilutive	0		0	0	0