Stock-Based Compensation (Restricted Stock Units and PBRSU) (Details) - $ / shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Restricted Stock Units (RSUs) [Member]
Number of Shares
Outstanding, Beginning of Period	1,380,000
Granted	939,354	772,238
Vested	(627,000)
Forfeited	(50,000)
Outstanding, End of Period	1,642,000
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Beginning Balance	$ 27.17
Granted, Weighted Average Grant Date Fair Value	35.33
Vested, Weighted Average Grant Date Fair Value	24.70
Forfeited, Weighted Average Exercise Price	30.22
Weighted Average Grant Date Fair Value, Ending Balance	$ 32.68
PBRSU [Member]
Number of Shares
Outstanding, Beginning of Period	903,000
Granted	222,788	367,558
Vested	(415,000)
Forfeited	(17,000)
Outstanding, End of Period	694,000
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Beginning Balance	$ 22.19
Granted, Weighted Average Grant Date Fair Value	34.01
Vested, Weighted Average Grant Date Fair Value	16.51
Forfeited, Weighted Average Exercise Price	29.94
Weighted Average Grant Date Fair Value, Ending Balance	$ 29.21