Business Segments - Schedule of Capital Expenditures by Segment (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting, Capital Expenditure Reconciling Item [Line Items]
Capital expenditures for property and equipment	$ 18	$ 169
Capital expenditures for property and equipment of continuing operations	18	29
Corporate and other [member]
Segment Reporting, Capital Expenditure Reconciling Item [Line Items]
Capital expenditures for property and equipment	8	4
Ownership [member]
Segment Reporting, Capital Expenditure Reconciling Item [Line Items]
Capital expenditures for property and equipment	$ 10	$ 25