A summary of long-term debt and capital leases by debt instrument follows:



	March 31, 2018		December 31, 2017
Senior Secured Credit Facility:
Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 2.75%	$	52,600	$	36,000
Term Loan B Facility due October 2023; bearing interest at LIBOR plus 2.50%	345,625		346,500
Tax-Exempt Bonds:
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 due December 2044 - fixed rate interest period through 2019; bearing interest at 3.75%	25,000		25,000
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 due December 2044 - fixed rate interest period through 2026; bearing interest at 3.125%	15,000		15,000
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25%	25,000		25,000
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125%	15,000		15,000
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 due April 2036 - fixed rate interest period through 2018; bearing interest at 4.75%	16,000		16,000
Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 due April 2029 - fixed rate interest period through 2019; bearing interest at 4.00%	11,000		11,000
Other:
Capital leases maturing through December 2107; bearing interest at up to 7.70%	6,713		5,595
Notes payable maturing through June 2027; bearing interest at up to 7.00%	2,522		2,585
Principal amount of long-term debt and capital leases	514,460		497,680
Less—unamortized discount and debt issuance costs (1)	14,489		15,178
Long-term debt and capital leases less unamortized discount and debt issuance costs	499,971		482,502
Less—current maturities of long-term debt	5,037		4,926
	$	494,934	$	477,576


(1)	A summary of unamortized discount and debt issuance costs by debt instrument follows:



	March 31, 2018		December 31, 2017
Revolving Credit Facility	$	3,682	$	3,938
Term Loan B Facility (including unamortized discount of $1,424 and $1,482)	7,101		7,392
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014	987		1,034
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2	496		511
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3	581		603
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1	673		691
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013	565		573
Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013	404		436
	$	14,489	$	15,178