Income Taxes - Quarter information (Detail) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
	Jan. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Taxes
Effective tax rate of income (loss) before income taxes		22.70%	31.70%
Income tax expense at U.S. federal statutory rate	21.00%			35.00%
Deferred income tax benefits included in income tax expense		$ 11	$ 32
Equity in net losses of unconsolidated entities		7	32
Investments Qualifying for Federal Tax Credits [Member]
Income Taxes
Equity in net losses of unconsolidated entities		6	6
Income tax (expense) benefit, including tax credits, from equity method investment		$ 10	$ 11