Shareholders' Equity - Additional Information (Detail) - $ / shares shares in Thousands			6 Months Ended
	May 07, 2019	May 08, 2018	Jun. 30, 2019	Jun. 30, 2018
Class of Stock [Line Items]
Expected common stock shares issued and outstanding			160,000
Date of declaration of dividends	May 07, 2019	May 08, 2018
Dividend declared per share	$ 0.50	$ 0.45
Date of dividend payment	Jun. 17, 2019	Jun. 15, 2018
Dividends payable to shareholders date of record	Jun. 03, 2019	Jun. 01, 2018
Discretionary Plan
Class of Stock [Line Items]
Shares repurchased			3,110	4,311
Average price per share			$ 73.45	$ 70.49
Non-Discretionary Plan
Class of Stock [Line Items]
Shares repurchased			88	1,411
Average price per share			$ 74.03	$ 72.21