Derivative Financial Instruments and Hedging Activities Fixed-to-Floating Interest Rate Swaps (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Notes due 2014 [Member]
Derivative [Line Items]
Notional amount	$ 100
Derivative, Fixed Interest Rate	5.95%
Derivative, Variable Interest Rate	2.98%
Basis for contracted floating interest rate paid	6 month LIBOR + 2.60%
Notes due 2017 [Member]
Derivative [Line Items]
Notional amount	150
Derivative, Fixed Interest Rate	5.30%
Derivative, Variable Interest Rate	4.43%
Basis for contracted floating interest rate paid	1 month LIBOR + 4.26%
Senior notes due 2017 [Member]
Derivative [Line Items]
Notional amount	450
Derivative, Fixed Interest Rate	1.50%
Derivative, Variable Interest Rate	0.62%
Basis for contracted floating interest rate paid	1 month LIBOR + 0.45%
Notes due 2018 [Member]
Derivative [Line Items]
Notional amount	415
Derivative, Fixed Interest Rate	5.60%
Derivative, Variable Interest Rate	3.54%
Basis for contracted floating interest rate paid	6 month LIBOR + 3.18%
Notes due 2019 [Member]
Derivative [Line Items]
Notional amount	300
Derivative, Fixed Interest Rate	6.95%
Derivative, Variable Interest Rate	5.32%
Basis for contracted floating interest rate paid	3 month LIBOR + 5.07%
Debentures due 2019 [Member]
Derivative [Line Items]
Notional amount	25
Derivative, Fixed Interest Rate	8.875%
Derivative, Variable Interest Rate	4.26%
Basis for contracted floating interest rate paid	6 month LIBOR + 3.84%
Debentures due 2020 [Member]
Derivative [Line Items]
Notional amount	150
Derivative, Fixed Interest Rate	3.875%
Derivative, Variable Interest Rate	2.29%
Basis for contracted floating interest rate paid	1 month LIBOR + 2.12%
Notes due 2021 [Member]
Derivative [Line Items]
Notional amount	150
Derivative, Fixed Interest Rate	3.47%
Derivative, Variable Interest Rate	2.01%
Basis for contracted floating interest rate paid	1 month LIBOR + 1.84%
Senior notes due 2022 [Member]
Derivative [Line Items]
Notional amount	1,100
Derivative, Fixed Interest Rate	2.75%
Derivative, Variable Interest Rate	0.71%
Basis for contracted floating interest rate paid	1 month LIBOR + 0.54%
Notes due 2023 [Member]
Derivative [Line Items]
Notional amount	150
Derivative, Fixed Interest Rate	3.68%
Derivative, Variable Interest Rate	1.22%
Basis for contracted floating interest rate paid	1 month LIBOR + 1.06%
Debentures due 2024 [Member]
Derivative [Line Items]
Notional amount	25
Derivative, Fixed Interest Rate	7.625%
Derivative, Variable Interest Rate	2.84%
Basis for contracted floating interest rate paid	6 month LIBOR + 2.48%
Debentures due 2029 [Member]
Derivative [Line Items]
Notional amount	50
Derivative, Fixed Interest Rate	7.65%
Derivative, Variable Interest Rate	2.92%
Basis for contracted floating interest rate paid	6 month LIBOR + 2.57%
Debentures due 2034 [Member]
Derivative [Line Items]
Notional amount	$ 25
Derivative, Fixed Interest Rate	5.45%
Derivative, Variable Interest Rate	0.64%
Basis for contracted floating interest rate paid	6 month LIBOR + 0.28%