Income Taxes - Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. federal statutory rate on income before income taxes	35.00%	35.00%	35.00%
Impact of foreign operations	(14.10%)	(13.50%)	(10.00%)
Impact of foreign divestiture		39.20%
Effects of statutory rate change	(8.50%)	(14.50%)
State income taxes, net of federal tax effect	2.10%	7.50%	4.80%
Permanent differences	1.80%	8.30%	4.20%
Transaction related items		25.90%
Change in valuation allowance	1.60%	2.80%	1.20%
Unrecognized tax benefit release	(0.80%)	(7.20%)
Other	(1.40%)	3.80%	(2.80%)
Effective income tax rate	15.70%	87.30%	32.40%