Stockholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Aug. 02, 2018	Nov. 17, 2016
Class Of Stock [Line Items]
Capitalized stock-based compensation costs	$ 0	$ 0
Stock options granted	0	0
Share issued, exercise of options and release of stock awards	1,100,000		1,600,000
Shares settled for tax withholding	508,000	609,000
Common stock repurchased, amount	$ 65,070,000	$ 57,599,000
November 2016 Stock Repurchase Program [Member]
Class Of Stock [Line Items]
Stock repurchase program, authorized amount					$ 200,000,000
Common stock repurchased, shares		4,100,000
Common stock repurchased, amount		$ 57,600,000
August 2018 Stock Repurchase Program [Member]
Class Of Stock [Line Items]
Stock repurchase program, authorized amount				$ 250,000,000
Common stock repurchased, shares	6.1
Common stock repurchased, amount	$ 64,900,000
Stock repurchase program, shares yet to be purchased	$ 148,100,000