Stock Incentive Plan (Schedule of Share-based Compensation, Unearned Compensation Related to RSU's) (Details) (Restricted Stock Units (RSUs) [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Changes In Unearned Compensation [Roll Forward]
Unearned compensation at beginning of year	$ 76,139	$ 46,801	$ 68,503
RSU's granted, net of cancellations	2,832	58,462	2,783
RSU's expensed	(27,566)	(27,035)	(24,988)
RSU's forfeiture adjustment	5,910	(2,089)	503
Unearned compensation at end of year	$ 57,315	$ 76,139	$ 46,801