Credit Facilities (Wells Fargo line of credit) (Details)	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2015 USD ($)	Feb. 03, 2015 USD ($)
Wells Fargo Bank | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			$ 20,000,000
Wells Fargo Bank | Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 7,500,000.0
Bank of America | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		20,000,000.0
Debt covenant, minimum current ratio	1.5
Bank of America | Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		10,000,000.0
Minimum | Bank of America | Revolving Credit Facility
Line of Credit Facility [Line Items]
Liquidation proceeds, credit derivative		$ 30,000,000
Cash conversion period		5 days