Selected Balance Sheet Data, Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Accounts Receivable, Net
Accounts receivable	$ 66,217		$ 64,180
Less allowance for bad debts	(5,821)		(4,911)
Accounts receivable, net	60,396	[1]	59,269	[1]
Accounts receivable from affiliates, net	$ 31		$ 1,595

[1] Accounts receivable, net includes an immaterial amount and $1,595 due from affiliates for 2014 and 2013, respectively.