Selected Balance Sheet Data, Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Accounts Receivable, Net
Accounts receivable	$ 78,073		$ 64,180
Less allowance for bad debts	(5,082)		(4,911)
Accounts receivable, net	72,991	[1]	59,269	[1]
Accounts receivable from affiliates, net	$ 48		$ 1,595

[1] Accounts receivable, net includes $48 and $1,595 due from affiliates as of March 31, 2014 and Dec. 31, 2013, respectively.