Treasury Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2017	Oct. 17, 2016
Equity, Class of Treasury Stock [Line Items]
Aggregate stock authorized for repurchase program (shares)		$ 300.0
Remaining authorized repurchase amount	$ 129.4
Treasury stock (shares)	64,800,000
2004 Amended and Restated Stock Incentive Plan
Equity, Class of Treasury Stock [Line Items]
Treasury shares issued (shares)	321,652
Issuance of treasury shares, average cost per share (usd per share)	$ 3.15
Shares repurchased to satisfy minimum employee withholding tax requirements resulting from the vesting of such restricted stock units (shares)	108,344
Average cost per share of treasury stock acquired (usd per share)	$ 30.30