Equipment, Property and Improvements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 85	$ 82	$ 83
Purchase of equipment, property and improvements, net	$ 80	73	$ 94
Industrial revenue bonds maturity period	10 years
Amount issued related to industrial revenue bonds	$ 350	$ 350