Summary of Significant Accounting Policies - Summary of Financial Information for Joint Ventures (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Method Investments and Joint Ventures [Abstract]
Total assets	$ 1,577	$ 1,231
Total liabilities	1,231	1,025
Revenues	606	491	$ 349
Net income	$ 71	$ 32	$ 7