Pension and Other Postretirement Benefits - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Employer Matching Contribution Percentage	6.00%
Defined contribution plan expense	$ 5	$ 6	$ 6
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension expense	17	18	29
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation	43	48
Pension expense	5	7	7
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension expense	2	7	7
Decrease in postemployment benefit liability	46
Expected pension benefits in 2016	11
Accumulated Benefit Obligation, continuing and discontinued operations	$ 100	$ 173	$ 174
Health Care Cost Trend Rate Assumed, Participants under 65	6.80%
Health Care Cost Trend Rate Assumed, Participants over 65	8.20%
Ultimate Health Care Cost Trend Rate	4.50%
Year that Rate Reaches Ultimate Trend Rate	2037
Amortization Period of Increase (Decrease) in Postemployement Obligation	8 years