Treasury And Common Stock - Schedule Of Treasury Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Class of Stock [Line Items]
Treasury Stock, Beginning Balance, Amount	$ (441,774)		$ (426,717)
Treasury stock purchases	(10,025)	[1]	(272)	[1]
Treasury Stock, Ending Balance, Amount	(451,799)
Treasury Stock, Shares, Beginning Balance	9,944,239		9,204,340
Treasury Stock, Shares, Ending Balance	10,542,820
Excluding Long-Term Incentive Plan [Member]
Class of Stock [Line Items]
Treasury stock purchases	(9,961)
Treasury stock purchased in connection with long-term incentive plan, Shares	594,582
Long-Term Incentive Plan [Member]
Class of Stock [Line Items]
Treasury stock purchases	(64)		(272)
Treasury Stock, Ending Balance, Amount			$ 426,989
Treasury stock purchased in connection with long-term incentive plan, Shares	3,999		8,294
Treasury Stock, Shares, Ending Balance			9,212,634

[1] This includes shares withheld in order to satisfy employee withholding taxes upon the distribution of vested restricted stock units.