Share-Based Compensation - Schedule of Share and Dividend Equivalent Share Award Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Value of share equivalents
Market price of Company's stock (in usd per share)	$ 75.85	$ 75.80
Phantom Stock and Performance Stock Units
Number of share equivalents
Balance at beginning of the period (in shares)	353,407,000	393,844,000
Granted (in shares)	174,991,000	140,804,000
Forfeited share equivalents (in shares)	(20,407,000)	(45,821,000)
Vested share equivalents (in shares)	(101,318,000)	(126,019,000)
Balance at end of the period (in shares)	406,673,000	362,808,000
Value of share equivalents
Balance at beginning of the period (in shares)	$ 22,717	$ 30,523
Granted (in shares)	13,273	10,673
Forfeited share equivalents (in shares)	1,548	3,473
Vested share equivalents (in shares)	7,647	10,519
Balance at end of the period (in shares)	$ 30,846	$ 27,501