Earnings Per Share - Details of Basic and Diluted Earnings Per Share (EPS) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 4,669	$ 933	$ 19,317	$ 16,562
Weighted average common shares outstanding used in basic EPS	43,287	43,134	43,327	43,050
Common shares issuable upon exercise of dilutive stock options and PSAs / RSUs	849	1,068	924	1,069
Weighted average common shares outstanding and common share equivalents used in diluted EPS	44,136	44,202	44,251	44,119
Earnings per share
Basic	$ 0.11	$ 0.02	$ 0.45	$ 0.38
Diluted	$ 0.11	$ 0.02	$ 0.44	$ 0.38