Income Taxes (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2011
Income Tax Contingency [Line Items]
Taxes Payable	$ 5,159	$ 404
Payment to the LP Unit holders of the cash tax savings, percent	85.00%
Retained percent of tax benefits	15.00%
Deferred Tax Assets-Non-Current	186,689	134,161
Amounts Due Pursuant to Tax Receivable Agreements	137,448	97,427
Additionally, increase in net deferred tax assets, before valuation allowance	7,387
Increase in deferred tax assets associated with changes in Accumulated Comprehensive Income (Loss)	3,046	419
Associated deferred tax assets	(342)	197
Valuation allowance	8,211	8,553
Net operating loss and tax credit carryforwards	4,168	27,109
Unrecognized tax benefits that would affect the effective tax rate	1,085	1,981
Unrecognized tax benefits accrued interest	136	199
Unrecognized tax benefits, recognized liability for penalties	255	561
Unrecognized tax benefits, recognized liability for interest	387	717
Unrecognized tax benefits accrued penalties		0
Amount decrease due to lapse of statute of limitation	(1,001)	(716)
Brazilian Subsidiary [Member]
Income Tax Contingency [Line Items]
Undistributed earnings of foreign subsidiaries	1,311
Offering [Member]
Income Tax Contingency [Line Items]
Common stock, shares issued	5,365	2,954	5,365
Deferred Tax Assets-Non-Current	47,481	36,959
Amounts Due Pursuant to Tax Receivable Agreements	40,360	31,415
Increase to Additional Paid-In-Capital	$ 7,122	$ 5,544