Consolidated Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for doubtful accounts receivable [Member]
Consolidated Valuation and Qualifying Accounts
Balance at beginning of period	$ 5,684	$ 8,753	$ 13,584
Charged to costs and expenses	(187)	8,678	4,973
Transferred from (to) allowance for notes receivable	46	(101)	(7,889)
Deductions	(744)	(11,646)	(1,915)
Balance at end of period	4,799	5,684	8,753
Allowance for doubtful notes receivable [Member]
Consolidated Valuation and Qualifying Accounts
Balance at beginning of period	254	7,950	134
Charged to costs and expenses		38
Transferred from (to) allowance for notes receivable	(46)	101	7,889
Deductions		(7,835)	(73)
Balance at end of period	$ 208	$ 254	$ 7,950