Stockholders' Equity - Additional Information (Detail) - USD ($)	12 Months Ended			34 Months Ended	89 Months Ended	101 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2014	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, authorized amount	$ 450,000,000.0			$ 450,000,000.0
Treasury stock, total repurchase during period (in shares)		10,488,000				11,142,000
Treasury stock, average price of share repurchased (in dollars per share)					$ 27.83	$ 27.57
Treasury stock, total cost of repurchased stock					$ 291,800,000	$ 307,200,000
Stock repurchase program, remaining amount available for repurchase	$ 142,800,000			$ 142,800,000
Dividends paid (usd per share)				$ 0.20
Cash dividends declared per share (in dollars per share)	$ 0.8	$ 0.8	$ 0.80
Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance awards, percentage of grant available to vest	0.00%
Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance awards, percentage of grant available to vest	100.00%
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	24 months
Shares reserved for grant	443,000			443,000
Maximum ownership percentage	5.00%			5.00%
Required weekly hours	20 hours
Award requisite service period	5 months
Maximum employee subscription rate	20.00%			20.00%
Purchase price of common stock, percent	85.00%
Maximum employee subscription amount	$ 25,000			$ 25,000
Rolling expiration period	24 months
2003 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive stock options granted to employees at exercise price	110.00%
Voting power of all classes of stock of the Company	10.00%
Expiration period	10 years
Vesting period	4 years
2003 Plan | Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive stock options granted to employees at exercise price	100.00%
Shares reserved for grant	700,000			700,000
2003 Plan | Non employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive stock options granted to employees at exercise price	85.00%
2003 Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Reduction to shares reserved for grant, ratio	0.015