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, 2012	Dec. 31, 2011	Dec. 31, 2010
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	$ 57,315	$ 76,139	$ 46,801
RSU's granted, net of cancellations	73,255	2,832	58,462
RSU's expensed	(25,728)	(26,303)	(25,584)
RSU's forfeiture adjustment	(11,189)	4,647	(3,540)
Unearned compensation at end of year	$ 93,653	$ 57,315	$ 76,139