Fair Value - Carrying Amounts and Estimated Fair Values of Long-Term Financial Instruments (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Assets:
Total financial assets, Carrying Amount	$ 88	$ 63
Liabilities:
Long-term debt, Carrying Amount	2,380	2,144
Total financial liabilities, Carrying Amount	2,380	2,144
Assets:
Total financial assets, Fair Value	88	63
Liabilities:
Total financial liabilities, Fair Value	2,499	2,178
Off-Balance sheet:
Surety bonds, Fair Value	13
Total off-balance sheet, Fair Value	90	112
Level 3 [Member]
Assets:
Other notes receivable, Carrying Amount	88	63
Assets:
Other notes receivable, Fair Value	88	63
Level 1 [Member]
Liabilities:
Long-term debt, Carrying Amount	2,380	2,144
Liabilities:
Long-term debt, Fair Value	2,499	2,178
Level 2 [Member]
Off-Balance sheet:
Letters of credit, Fair Value	77	80
Surety bonds, Fair Value	$ 13	$ 32