Stock-Based Compensation- Restricted Stock and Restricted Stock Units Activity (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares outstanding, Beginning balance	3,705,000	2,809,000	2,480,000
Granted	803,000	2,728,000	1,773,000
Forfeited	(485,000)	(637,000)	(378,000)
Vested	(1,176,000)	(1,195,000)	(1,066,000)
Non-vested shares outstanding, Ending balance	2,847,000	3,705,000	2,809,000
Non-vested shares outstanding, Weighted Average Grant Date Fair Value per Share, Beginning balance	$ 33.31	$ 43.31	$ 49.52
Granted, Weighted Average Grant Date Fair Value per Share	$ 25.42	$ 27.24	$ 35.29
Forfeited, Weighted Average Grant Date Fair Value per Share	$ 25.14	$ 39.47	$ 47.34
Vested, Weighted Average Grant Date Fair Value per Share	$ 36.64	$ 39.64	$ 41.70
Non-vested shares outstanding, Weighted Average Grant Date Fair Value per Share, Ending balance	$ 30.05	$ 33.31	$ 43.31
Service - Based Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares outstanding, Beginning balance	2,999,000	2,371,000	2,123,000
Granted	465,000	2,428,000	1,589,000
Forfeited	(416,000)	(605,000)	(364,000)
Vested	(1,146,000)	(1,195,000)	(977,000)
Non-vested shares outstanding, Ending balance	1,902,000	2,999,000	2,371,000
Performance Market Based Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested shares outstanding, Beginning balance	706,000	438,000	357,000
Granted	338,000	300,000	184,000
Forfeited	(69,000)	(32,000)	(14,000)
Vested	(30,000)	0	(89,000)
Non-vested shares outstanding, Ending balance	945,000	706,000	438,000