Income Taxes (Net Current And Non-Current Deferred Tax Assets And Liabilities (By Segment)) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Current deferred tax asset	$ 27,154	$ 15,201
Valuation allowance	(84)	(83)
Current deferred tax liability	(1,095)	(816)
Net current deferred tax asset (liability)	25,975	14,302
Non-current deferred tax asset	58,929	23,989
Valuation allowance	(8,623)	(7,092)
Non-current deferred tax liability	(27,205)	(26,450)
Net non-current deferred tax asset (liability)	23,101	(9,553)
Net deferred tax asset	49,076	4,749
U.S. [Member]
Income Taxes [Line Items]
Current deferred tax asset	26,928	15,013
Current deferred tax liability	(64)	(63)
Net current deferred tax asset (liability)	26,864	14,950
Non-current deferred tax asset	44,355	11,461
Non-current deferred tax liability	(22,143)	(21,662)
Net non-current deferred tax asset (liability)	22,212	(10,201)
Net deferred tax asset	49,076	4,749
U.K. [Member]
Income Taxes [Line Items]
Current deferred tax asset	104	110
Valuation allowance	(73)	(72)
Current deferred tax liability	(1,031)	(753)
Net current deferred tax asset (liability)	(1,000)	(715)
Non-current deferred tax asset	12,163	10,421
Valuation allowance	(8,229)	(6,801)
Non-current deferred tax liability	(2,934)	(2,905)
Net non-current deferred tax asset (liability)	1,000	715
Other International [Member]
Income Taxes [Line Items]
Current deferred tax asset	122	78
Valuation allowance	(11)	(11)
Net current deferred tax asset (liability)	111	67
Non-current deferred tax asset	2,411	2,107
Valuation allowance	(394)	(291)
Non-current deferred tax liability	(2,128)	(1,883)
Net non-current deferred tax asset (liability)	$ (111)	$ (67)