Long-Term Debt (Tables)

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Schedule of Long-Term Debt

Long-term debt at March 31, 2021 and December 31, 2020 consisted of the following:  

(in thousands)	March 31, 2021			December 31, 2020
Current portion of long-term debt:
Current portion of 5-year term loan facility expires 2022	$	40,000		$	40,000
Current portion of 5-year term loan facility expires 2023		30,000			30,000
Total current portion of long-term debt		70,000			70,000
Long-term debt:
Note agreements:
4.200% senior notes, semi-annual interest payments, net of the unamortized discount,    balloon due 2024	$	499,455		$	499,416
4.500% senior notes, semi-annual interest payments, net of the unamortized discount,    balloon due 2029		349,555			349,540
2.375% senior notes, semi-annual interest payments, net of the unamortized discount,    balloon due 2031		699,270			699,252
Total notes		1,548,280			1,548,208
Credit agreements:
5-year term-loan facility, periodic interest and principal payments, LIBOR plus up to    1.750%, expires June 28, 2022		240,000			250,000
5-year revolving-loan facility, periodic interest payments, LIBOR plus up to 1.500%, plus    commitment fees up to 0.250%, expires June 28, 2022		—			—
5-year term-loan facility, periodic interest and principal payments, LIBOR plus up to    1.750%, expires December 21, 2023		232,500			240,000
Total credit agreements		472,500			490,000
Debt issuance costs (contra)		(11,680	)		(12,302	)
Total long-term debt less unamortized discount and debt issuance costs		2,009,100			2,025,906
Current portion of long-term debt		70,000			70,000
Total debt	$	2,079,100		$	2,095,906