Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 1,368	$ 657	$ 1,329
Charged to Cost and Expenses	354	941	244
Credited to Other Accounts	134	(65)	(67)
Amount Written Off	(447)	(165)	(849)
Balance at End of Period	1,409	1,368	657
Accounts Receivable
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	1,206	490	722
Charged to Cost and Expenses	453	941	195
Credited to Other Accounts	28	(60)	(67)
Amount Written Off	(447)	(165)	(360)
Balance at End of Period	1,240	1,206	490
Investment in Sales-Type Leases
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	162	167	607
Charged to Cost and Expenses	(99)	0	49
Credited to Other Accounts	106	(5)	0
Amount Written Off	0	0	(489)
Balance at End of Period	$ 169	$ 162	$ 167