Condensed, Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 35,778,000	$ 40,065,000	$ 72,099,000	$ 70,561,000
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustment	(1,369,000)	47,000	(442,000)	296,000
Adjustment for Long-term Intercompany Transactions, Gross of Tax	(178,000)	48,000	47,000	237,000
Adjustment for Long-term Intercompany Transactions, Tax Benefit (Expense)	70,000	(19,000)	(18,000)	(92,000)
Other Comprehensive Income (Loss), Net of Tax	(1,477,000)	76,000	(413,000)	441,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	34,301,000	40,141,000	71,686,000	71,002,000
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1,458,000)	(453,000)	(2,534,000)	(2,110,000)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	32,843,000	39,688,000	69,152,000	68,892,000
Comprehensive Income Attributable To Redeemable Noncontrolling Interests			$ 1,300,000	$ 1,100,000