- Notes Payable (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Short-term Debt [Line Items]
Outstanding borrowings at end of year	$ 58		$ 81
Notes Payable Current
Short-term Debt [Line Items]
Outstanding borrowings at end of year	58	[1]	81	[1]
Weighted average interest rate on outstanding borrowings at end of year(b)	2.60%	[1],[2]	4.40%	[1],[2]
Approximate maximum month-end outstanding borrowings during year	124	[1]	177	[1]
Approximate average month-end outstanding borrowings during year	$ 107	[1]	$ 116	[1]
Weighted average interest rate on average month-end outstanding borrowings during year(b)	4.00%	[1],[2]	4.70%	[1],[2]

[1] Includes borrowings under both committed credit facilities and uncommitted lines of credit and similar arrangements.

[2] This calculation does not include the commitment fees to be paid on the unused revolving credit facility balances which are recorded as interest expense for accounting purposes.