Shareholders' Equity - Additional Information (Detail) - USD ($)		12 Months Ended				48 Months Ended
	Dec. 12, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2017	Dec. 31, 2018	Mar. 28, 2018	Mar. 14, 2018	Jul. 20, 2015	Jul. 21, 2014
Accelerated Share Repurchases [Line Items]
Common Stock, Shares Authorized		560,000,000				560,000,000	560,000,000
Common Stock, Par or Stated Value Per Share		$ 0.10				$ 0.10	$ 0.10	$ 0.10
Stock Repurchase Program, Authorized Amount							$ 100,000,000.0
Common Stock, Shares, Outstanding		276,210,910				276,210,910	279,583,006
Treasury stock shares (in shares)		10,718,319				10,718,319	13,796,696
Fair value of common stock repurchased		$ 386,322,000				$ 386,322,000	$ 477,572,000
Accelerated Share Repurchases, Settlement (Payment) or Receipt							20,000,000.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount							147,500,000
Treasury Stock, Shares, Acquired						13,800,000
Accelerated Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Treasury stock shares (in shares)		2,883,349	209,618	5,408,819	2,384,760	2,883,349
Treasury Stock Acquired, Average Cost Per Share		$ 48.51	$ 36.53	$ 32.35	$ 31.46
Fair value of common stock repurchased		$ 139,900,000	$ 7,700,000	$ 175,000,000.0	$ 75,000,000.0	$ 139,900,000	80,000,000.0
Treasury Stock, Shares, Acquired	2,910,150
Maximum [Member]
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount							$ 100,000,000.0			$ 400,000,000.0	$ 200,000,000.0
2 for 1 Stock Split [Member]
Accelerated Share Repurchases [Line Items]
Common Stock, Shares Authorized								560,000,000	280,000,000
Common Stock, Shares, Outstanding								276,000,000	138,000,000