Receivables (Rollforward of Allowance for Doubtful Accounts) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts [Roll Forward]
Balance as of beginning of period	$ 6,039	$ 3,823
Current period provision	543	3,457
Direct write-offs charged against the allowance	(365)	(1,241)
Balance as of end of period	$ 6,217	$ 6,039