Share-Based Compensation (RSU Activity During the Year) (Details) (Restricted Stock Units (RSUs) [Member], USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restricted Stock Units (RSUs) [Member]
Outstanding and unvested, beginning balance, in shares	1,300,174	864,756	0
RSUs, granted, in shares	672,185	839,865	921,182
RSUs, vested, in shares	(512,614)	(290,868)	(6,521)
RSUs, cancelled, in shares	(152,572)	(113,579)	(49,905)
Outstanding and unvested, ending balance, in shares	1,307,173	1,300,174	864,756
Weighted average grant date fair value, beginning of Period, in dollars per share	$ 26.14	$ 16.85	$ 0
Weighted average grant date fair value, granted, in dollars per share	$ 43.87	$ 32.22	$ 16.85
Weighted average grant date fair value, vested, in dollars per share	$ 24.20	$ 16.95	$ 16.85
Weighted average grant date fair value, cancelled, in dollars per share	$ 34.87	$ 23.71	$ 16.85
Weighted average grant date fair value, end of Period, in dollars per share	$ 35.00	$ 26.14	$ 16.85