Long-Term Debt (Tables)

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

Outstanding Long-Term Debt

Our outstanding long-term debt is shown below: 

	March 31,		December 31,
(in thousands)	2022		2021
Uncollateralized senior notes:
5.93% note, due October 31, 2023	$	6,000	$	6,000
5.68% note, due June 30, 2026	14,500		14,500
6.43% note, due May 2, 2028	4,900		4,900
3.73% note, due December 16, 2028	14,000		14,000
3.88% note, due May 15, 2029	40,000		40,000
3.25% note, due April 30, 2032	70,000		70,000
3.48% note, due May 31, 2038	50,000		50,000
3.58% note, due November 30, 2038	50,000		50,000
3.98% note, due August 20, 2039	100,000		100,000
2.98% note, due December 20, 2034	70,000		70,000
3.00% note, due July 15, 2035	50,000		50,000
2.96% note, due August 15, 2035	40,000		40,000
2.49% notes Due January 25, 2037	50,000		50,000
2.95% notes Due March 15, 2042	50,000		—
Equipment security note
2.46% note, due September 24, 2031	9,165		9,378
Less: debt issuance costs	(970)		(913)
Total long-term debt	617,595		567,865
Less: current maturities	(19,717)		(17,962)
Total long-term debt, net of current maturities	$	597,878	$	549,903

Schedule of Line of Credit Facilities [Line Items]

Schedule of Line of Credit Facilities [Table Text Block]

(in thousands)	Total Borrowing Capacity		Less: Amount of Debt Issued		Less: Unfunded Commitments		Remaining Borrowing Capacity
Shelf Agreement
Prudential Shelf Agreement (1)	$	370,000	$	(220,000)	$	—	$	150,000
MetLife Shelf Agreement (1)	150,000		(50,000)		—		100,000
Total Shelf Agreements as of March 31, 2022	$	520,000	$	(270,000)	$	—	$	250,000