Receivables Rollforward of Allowance for Doubtful Accounts (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended			12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Installment Receivables [Member]	Dec. 31, 2013 Installment Receivables [Member]
Allowance for Doubtful Accounts [Roll Forward]
Balance as of January 1	$ 6,039		$ 6,039	$ 3,823
Current period provision	1,143	1,603	705	3,457
Direct write-offs charged against the allowance			(265)	(1,241)
Balance as of December 31	$ 6,479		$ 6,479	$ 6,039