Derivative Financial Instruments (Details) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2007 USD ($)	Dec. 31, 2015	Dec. 31, 2013 USD ($)
Interest Rate Swap
Derivative
Gain (Loss) on interest rate swap agreements not designated as hedging instruments			$ (2)
Parent Company [Member]
Derivative
Interest rate swaps, number of instruments	2
Interest rate swaps, notional amount	$ 1,000
Basis of interest payment	three month LIBOR	three month LIBOR
Parent Company [Member] | Interest Rate Swap, Agreement One
Derivative
Basis of interest payment	three month LIBOR
Parent Company [Member] | Interest Rate Swap, Agreement Two
Derivative
Interest rate swaps, notional amount	$ 500
Basis of interest payment	three month LIBOR