Credit Agreements and Senior Notes (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Summary of Interest Rate Margins and Fees Payable Under the Amended and New Credit Agreements

The following summarizes the interest rate margins and fees payable under the Credit Agreements, based on our current long-term credit ratings:

	Amended Credit Facility	$950 Million Credit Facility
Revolving Loans:
ABR	0.25% over the greater of (i) the prime rate, (ii) the federal funds rate plus 0.50% and (iii) the daily one-month Eurodollar Rate plus 1.00%	3.25% over the greater of (i) the prime rate, (ii) the federal funds rate plus 0.50% and (iii) the daily one-month Eurodollar Rate plus 1.00%
Eurodollar	1.25% over specified LIBOR	4.25% over specified LIBOR
Swingline Loans	N/A	At our option, at a rate per annum equal to (i) the ABR plus the applicable interest margin for ABR loans or (ii) the daily one-month Eurodollar Rate plus the applicable interest margin for Eurodollar loans
Letter of credit participation fees:
Performance letters of credit	N/A	2.125% per annum
All other letters of credit	N/A	4.25% per annum
Commitment fee on unused commitments under credit agreement	0.20% per annum	0.70% per annum

Summary of Senior Notes

At December 31, 2019, our senior notes were comprised of the following debt issues (dollars in millions):

										Semiannual
	Principal			Interest Rate						Interest Payment
Debt Issue	Amount		Maturity Date	Coupon			Effective			Dates
3.45% Senior Notes due 2023	$	250.0	November 1, 2023		3.45	%		3.50	%	May 1 and November 1
7.875% Senior Notes due 2025	$	500.0	August 15, 2025		7.875	%		8.00	%	February 15 and August 15
5.70% Senior Notes due 2039	$	500.0	October 15, 2039		5.70	%		5.75	%	April 15 and October 15
4.875% Senior Notes due 2043	$	750.0	November 1, 2043		4.875	%		4.89	%	May 1 and November 1

Summary of Carrying Value of Senior Notes, Net of Unamortized Discount and Debt Issuance Costs

At December 31, 2019 and 2018, the carrying value of our senior notes, net of unamortized discount and debt issuance costs, was as follows (in thousands):

	December 31,
	2019		2018
3.45% Senior Notes due 2023	$	248,759	$	248,455
7.875% Senior Notes due 2025		491,655		490,491
5.70% Senior Notes due 2039		493,316		493,139
4.875% Senior Notes due 2043		742,011		741,837
Total senior notes, net	$	1,975,741	$	1,973,922

Aggregate Maturities of Senior Notes, Excluding Net Unamortized Discounts and Debt Issuance Costs

As of December 31, 2019, the aggregate annual maturity of our senior notes, excluding net unamortized discounts and debt issuance costs of $7.0 million and $17.3 million, respectively, was as follows (in thousands):

	Aggregate Principal Amount
Year Ending December 31,
2020	$	—
2021		—
2022		—
2023		250,000
2024		—
Thereafter		1,750,000
Total maturities of senior notes	$	2,000,000