Condensed, Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 36,321	$ 30,496
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustment	927	249
Adjustment for Long-term Intercompany Transactions, Gross of Tax	225	189
Adjustment for Long-term Intercompany Transactions, Tax Benefit (Expense)	(88)	(73)
Other Comprehensive Income (Loss), Net of Tax	1,064	365
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	37,385	30,861
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	1,076	1,657
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	36,309	29,204
Comprehensive Income Attributable To Redeemable Noncontrolling Interests	$ 510	$ 1,200