Schedule II - Valuation and Qualifying Accounts (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 871,000	$ 3,210,000	$ 1,554,000
Additions	7,256,000	0	1,829,000
Deductions	(642,000)	(2,339,000)	(173,000)
Ending balance		871,000	3,210,000
Allowance for doubtful accounts	7,485,000	871,000	3,210,000
Allowance for Loan and Lease Losses [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	0	0	3,777,000
Additions	0	0	0
Deductions	0	0	(3,777,000)
Ending balance	$ 0	$ 0	$ 0