Other Data (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
State Income Tax Expense
Texas gross margin tax	$ 459	$ 528	$ 464
Michigan gross receipts deferred tax liability	(170)	(90)	45
Other	193	116	57
Total state income tax expense	482	554	566
State income tax payments, net of refunds and collections	$ 522	$ 533	$ 674