Fair Value Measurement Fair Value Measurement - Schedule of Liabilities Measured at Fair Value on Recurring Basis Quantitative Information about Level 3 Fair Value Measurements (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative Liabilities, Gross Amount	$ 472	$ 339
Fair Value, Measurements, Recurring [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative Liabilities, Gross Amount	472	339
Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative Liabilities, Gross Amount	35	$ 43
Fair Value, Measurements, Recurring [Member] | Level 3 | Derivative liabilities
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Derivative Liabilities, Gross Amount	$ 35
Fair Value, Measurements, Recurring [Member] | Level 3 | Derivative liabilities | Minimum [Member] | Discounted cash flows
Fair Value Inputs [Abstract]
Swap rates (percent)	2.00%	2.00%
Fair Value, Measurements, Recurring [Member] | Level 3 | Derivative liabilities | Maximum [Member] | Discounted cash flows
Fair Value Inputs [Abstract]
Swap rates (percent)	2.00%	3.00%
Fair Value, Measurements, Recurring [Member] | Level 3 | Derivative liabilities | Weighted Average | Discounted cash flows
Fair Value Inputs [Abstract]
Swap rates (percent)	2.00%	2.00%