Stockholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued in conjunction with the vesting and release of restricted stock units			135,872
Common stock issued due to exercise of stock options			114,107
Common stock issued in connection with employee stock purchase plan			18,280
Employee stock purchase plan, net proceeds			$ 2,400,000
Repurchase of common stock, shares			68,185
Repurchase of common stock	2,000,000		1,951,000	858,000
Amount available under the share repurchase program			50,000,000
Shares repurchase under the share repurchase program	0		0
Share-based compensation expense recognized	1,300,000	1,900,000	3,500,000	4,000,000
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized	1,000,000	1,000,000	2,400,000	2,300,000
Total unrecognized compensation expense related to non-vested stock options	7,600,000		7,600,000
Expected weighted-average period of recognition for unrecognized compensation expense	2 years 6 months 18 days
Weighted-average grant date fair value of stock options granted			$ 10.96	$ 9.19
Stock options granted			535,128	529,134
Restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized	300,000	900,000	1,100,000	1,700,000
Expected weighted-average period of recognition for unrecognized compensation expense	2 years 9 months 18 days
Total unrecognized compensation expense related to non-vested restricted stock	$ 1,800,000		$ 1,800,000
Weighted-average grant date fair value of restricted stock granted			$ 25.46	$ 23.18
Restricted stock granted			108,030	68,994