Income Taxes (Federal Statutory Income Tax Rate To Income Before Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Income Taxes [Abstract]
Income (loss) before income taxes	$ 50,032		$ (47,953)		$ 9,258
Partnership (income) loss not subject to tax	(60,304)		47,357		(7,822)
Income (loss) subject to income taxes	(10,272)		(596)		1,436
Tax (benefit) expense at federal statutory rate	(3,595)		(209)		503
State income taxes, net of federal benefit	123		583		991
Effects of unrecognized tax positions, federal and state	1,964		1,909		1,733
Return to provision, federal and state	72		257		(224)
Other	219		48		77
Total income tax expense (benefit)	$ (1,217)		$ 2,588		$ 3,080
Effective tax rate on income (loss) before income taxes	(1.00%)	[1]	(1.00%)	[1]	33.00%

[1] Income tax expense is related to taxable income generated by our corporate subsidiaries and Texas Margin Tax. Due to the income tax benefit in 2011 and the loss before income taxes in 2010, the effective tax rate as a percentage of our total income (loss) before income taxes is not meaningful.