Debt (Details Textual) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2017	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Debt Instrument [Line Items]
Loss on debt extinguishments		$ 0	$ (1,282)	$ 0	$ (1,282)
Book value		277,873		277,873		$ 272,751
Senior Notes due 2024
Debt Instrument [Line Items]
Net unamortized debt issuance costs		2,600		2,600		3,100
Debt Instrument, Face Amount	$ 250,000
Proceeds from Debt	$ 245,000
Revolving Credit Facility
Debt Instrument [Line Items]
Net unamortized debt issuance costs		$ 1,700		$ 1,700		$ 2,300
Stated interest rate		2.70%		2.70%
Book value		$ 20,000		$ 20,000
Line of Credit Facility, Remaining Borrowing Capacity		209,500		209,500
Line of Credit Facility, Maximum Borrowing Capacity		250,000		250,000
Letters of Credit Outstanding, Amount		$ 20,500		$ 20,500