Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL			$ 1,081
Other comprehensive (loss) income before reclassifications	$ 5	$ 1	12	$ 4
Amounts reclassified from AOCL	(1)	(1)	(3)	(3)
Income tax	1	0	2	1
Net current period other comprehensive (loss) income	5	0	11	2
Total AOCL	555		555
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL	(8)	(6)	(7)	(6)
Other comprehensive (loss) income before reclassifications	(1)	0	(2)	0
Income tax	1	0	1	0
Net current period other comprehensive (loss) income	0	0	(1)	0
Total AOCL	(8)	(6)	(8)	(6)
Accumulated defined benefit plans adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL	(19)	(21)	(18)	(20)
Amounts reclassified from AOCL	(1)	(1)	(3)	(3)
Income tax	0	0	1	1
Net current period other comprehensive (loss) income	(1)	(1)	(2)	(2)
Total AOCL	(20)	(22)	(20)	(22)
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL	(30)	(30)	(38)	(33)
Other comprehensive (loss) income before reclassifications	6	1	14	4
Net current period other comprehensive (loss) income	6	1	14	4
Total AOCL	(24)	(29)	(24)	(29)
Accumulated Other Comprehensive Income (Loss), net of tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL	(57)	(57)	(63)	(59)
Total AOCL	$ (52)	$ (57)	$ (52)	$ (57)