Accounts Receivable and Allowances for Doubtful Accounts (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current and long-term accounts receivable balances
Accounts receivable	$ 46,851	$ 99,686
Installment contract receivables, short-term	33,146	37,086
Long-term receivables	7,555	11,371
Total receivables	$ 87,552	$ 148,143