Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	162.40%	30.90%
Estimated annual effective tax rate	72.20%	30.50%
Effective federal statutory tax rate	21.00%	21.00%
Income tax expense benefits on domestic and foreign losses valuation reserves	$ 0	$ 0
Provision for income taxes	150,000,000	151,000,000
Income before income taxes	92,000,000	491,000,000
Income tax on pre-tax income at annual tax rate	67,000,000	150,000,000
Unfavorable impact income taxes	$ 83,000,000	$ 1,000,000