Stock-Based Compensation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		0 Months Ended		0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Performance Shares	Jun. 30, 2013 Performance Shares	Jun. 30, 2014 Performance Shares	Jun. 30, 2013 Performance Shares	Jun. 06, 2012 Employee Stock Purchase Plan	Jun. 30, 2014 Employee Stock Purchase Plan	Jun. 12, 2013 2008 Equity Incentive Plan	Jun. 06, 2012 2008 Equity Incentive Plan	Jun. 30, 2014 2008 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares of common stock authorized for issuance										500,000		6,000,000	3,000,000
Maximum number of shares of common stock authorized for issuance										1,320,500		19,540,940
Number of shares available for future issuance	17,700,000		17,700,000								500,000			5,600,000
Performance-based stock options awards	$ 1,341	$ 841	$ 2,286	$ 1,554		$ 0	$ 0	$ 0	$ 0
Performance-based stock options, outstanding	12,018,000		12,018,000		10,405,000	0		0