Treasury Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2019	Oct. 17, 2016
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, additional repurchase authorization		$ 300.0
Remaining authorized repurchase amount	$ 124.6
Treasury stock (shares)	63,936,650
2004 Amended and Restated Stock Incentive Plan
Equity, Class of Treasury Stock [Line Items]
Treasury shares issued for restricted stock units that vested during the period	1,281,777
Average cost of treasury shares that were issued for restricted stock units that vested during the period (usd per share)	$ 2.86
Shares repurchased to satisfy minimum employee withholding tax requirements resulting from the vesting of such restricted stock units (shares)	535,527
Average cost per share of treasury stock acquired to satisfy minimum employee withholding requirements (usd per share)	$ 28.48