Earnings Per Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]
Net income from continuing operations	$ 17,475	$ 15,545
Loss from discontinued operations		(219)
Net income	$ 17,475	$ 15,326
Weighted average common shares outstanding	37,121	36,774
Income from continuing operations	$ 0.47	$ 0.42
Loss from discontinued operations
Net income per common share	$ 0.47	$ 0.42
Weighted average common shares outstanding	37,121	36,774
Dilutive effect of stock options and restricted stock	975	899
Diluted weighted average shares outstanding	38,096	37,673
Income from continuing operations	$ 0.46	$ 0.41
Loss from discontinued operations
Diluted earnings per share	$ 0.46	$ 0.41