Stock Incentive Plans (Details 2) (USD $) Share data in Thousands, except Per Share data	6 Months Ended
	Jun. 30, 2011
Stock Options [Member]
Non-vested stock incentive awards
Beginning Balance, Non-vested, shares	768
Beginning of Period, Non-vested , Weighted Average Grant Date Fair Value	$ 6.19
Vested, shares	(220)
Vested, Weighted Average Grant Date Fair Value	6.12
Granted, shares	289
Granted, Weighted Average Grant Date Fair Value	$ 9.60
Terminated, shares	(6)
Terminated, Weighted Average Grant Date Fair Value	$ 5.54
Ending Balance, Non-vested, shares	831
Ending of Period, Non-vested, Weighted Average Grant Date Fair Value	7.40
Restricted Stock [Member]
Non-vested stock incentive awards
Beginning Balance, Non-vested, shares	420
Beginning of Period, Non-vested , Weighted Average Grant Date Fair Value	41.09
Vested, shares	(145)
Vested, Weighted Average Grant Date Fair Value	41.86
Granted, shares	242
Granted, Weighted Average Grant Date Fair Value	$ 49.19
Terminated, shares	(6)
Terminated, Weighted Average Grant Date Fair Value	$ 26.31
Ending Balance, Non-vested, shares	511
Ending of Period, Non-vested, Weighted Average Grant Date Fair Value	$ 44.86