Receivables - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended		1 Months Ended
	Mar. 31, 2012	Dec. 31, 2014 Agreement	Dec. 31, 2013	May 30, 2013
Schedule Of Financial Receivables [Line Items]
Number of arrangement with different financial institution to sell customer receivables		3
Number of additional financial institution				2,000,000
Sale of customer receivables	$ 304,000,000
Cash received for receivables	50,000,000
Deferred purchase price receivable	254,000,000	356,000,000	248,000,000
Additional funding received		40,000,000	5,000,000
Amount of cash draws under arrangement		710,000,000	388,000,000
Amount of cash repayments under arrangement		670,000,000	383,000,000
Gross cash outflows from deferred purchased receivables		7,381,000,000	6,985,000,000
Gross cash inflows from deferred purchased receivables		7,272,000,000	6,755,000,000
Accounts receivables		17,705,000,000
Cash collections		17,098,000,000
Minimum [Member]
Schedule Of Financial Receivables [Line Items]
Funding of customer receivables sold		50,000,000
Funding of customer receivables sold after amendment				200,000,000
Maximum [Member]
Schedule Of Financial Receivables [Line Items]
Funding of customer receivables sold		250,000,000
Funding of customer receivables sold after amendment				500,000,000
Since Inception [Member]
Schedule Of Financial Receivables [Line Items]
Additional funding received		200,000,000
Amount of cash draws under arrangement		1,258,000,000
Amount of cash repayments under arrangement		$ 1,058,000,000