Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions		1 Months Ended		3 Months Ended
	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Apr. 25, 2018	Sep. 30, 2017
Stockholders Equity Note [Line Items]
Dividend paid date				Jun. 15, 2018
Dividend record date				Jun. 09, 2018
Dividends paid		$ 68,000,000	$ 63,000,000
Dividends paid per share		$ 0.12	$ 0.11
Repurchase of common stock				$ 362,400,000
Subsequent Event [Member]
Stockholders Equity Note [Line Items]
Dividends declared per share					$ 0.12
Share Repurchase Program [Member]
Stockholders Equity Note [Line Items]
Authorized amount of stock repurchase						$ 1,000,000,000
Repurchase of common stock, remaining amount		$ 310,000,000		$ 310,000,000
Share Repurchase Program [Member] | Common Stock [Member]
Stockholders Equity Note [Line Items]
Common stock repurchases, Shares		10
Stock repurchased/issued price per share		$ 36.24		$ 36.24
Repurchase of common stock		$ 362,000,000
Share Repurchase Program [Member] | Common Stock [Member] | Subsequent Event [Member]
Stockholders Equity Note [Line Items]
Common stock repurchases, Shares	10
Stock repurchased/issued price per share	$ 31.38
Repurchase of common stock	$ 310,000,000