Stockholders' Equity - Additional Information (Detail) (USD $)	1 Months Ended	6 Months Ended	12 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended		6 Months Ended
	Aug. 31, 2007	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Minimum	Jun. 30, 2013 Performance Shares Minimum	Jun. 30, 2013 Performance Shares Maximum	Aug. 31, 2003 Employee Stock Purchase Plan	Jun. 30, 2013 Employee Stock Purchase Plan	Jun. 30, 2008 Employee Stock Purchase Plan	Jun. 30, 2013 Employee Stock Purchase Plan Minimum H	Jun. 30, 2013 Employee Stock Purchase Plan Maximum	Jun. 30, 2013 2003 Plan Employee Stock Options unit_per_share	Jun. 30, 2013 2003 Plan Employee Stock Options Minimum	Jun. 30, 2013 2003 Plan Employee Stock Options	Jun. 30, 2013 2003 Plan Employee Stock Options Non Employee Stock Options
Schedule of Trading Securities and Other Trading Assets [Line Items]
Stock repurchase program, authorized amount	$ 100,000,000
Treasury stock, total repurchase during period (in shares)		645,000	645,000
Treasury stock, average price of share repurchased (in dollars per share)		$ 16.26	$ 16.26
Treasury stock, total cost of repurchased stock		10,500,000	10,500,000
Stock repurchase program, remaining amount available for repurchase		89,500,000
Stock repurchase program, expected amount to be executed during next twelve months				16,000,000
Incentive stock options granted to employees at exercise price												110.00%		100.00%	85.00%
Voting power of all classes of stock of the Company													10.00%
Options granted term, years												10 years
Vesting period, years												4 years
Reduction in number of shares for grant under plan, equity award per share (in restricted stock per share)												1.5
Shares reserved for grant								327,000				4,983,000
Performance awards, percentage of grant available to vest					0.00%	100.00%
Common stock reserved for employee stock purchase plan							200,000		200,000
Plan requirement for annual common stock reserve increase							200,000
Percentage of outstanding share							1.00%
Employee Stock Purchase Plan, offering period								24 months
Employee Stock Purchase Plan, offering period membership, percentage of voting stock											5.00%
Employee Stock Purchase Plan, offering period membership, required number of hours worked per week (in hours)										20
Employee Stock Purchase Plan, offering period membership, required period of customary employment during calendar year										5 months
Contribution under ESPP plan								20.00%
Purchase price per share for stock purchase under ESPP								85.00%
Common stock purchase authorized per year								$ 25,000
Employee Stock Purchase Plan, purchase period								6 months