Investments of Insurance Subsidiaries - Schedule of Maturities of Investments (Detail) $ in Millions	Jun. 30, 2015 USD ($)
Amortized Cost and Fair Value Debt Securities [Abstract]
Due in one year or less, Amortized Cost	$ 79
Due after one year through five years, Amortized Cost	165
Due after five years through ten years, Amortized Cost	121
Due after ten years, Amortized Cost	100
Amortized Cost, Total	465
Due in one year or less, Fair Value	80
Due after one year through five years, Fair Value	168
Due after five years through ten years, Fair Value	126
Due after ten years, Fair Value	104
Fair Value, Total	$ 478