Investments of Insurance Subsidiaries - Schedule of Maturities of Investments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	$ 110
Due after one year through five years, Amortized Cost	180
Due after five years through ten years, Amortized Cost	100
Due after ten years, Amortized Cost	89
Amortized Cost, Total	479
Amortized Cost	498
Due in one year or less, Fair Value	110
Fair Value	510	570
Due after one year through five years, Fair Value	186
Due after five years through ten years, Fair Value	102
Due after ten years, Fair Value	89
Fair Value, Total	487
Fair Value	506
Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7
Fair Value	7
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12
Fair Value	$ 12