Financing and Other Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Principal	$ 3,041,989	$ 3,132,090
Current portion of gross debt	193,169	170,556
Less: Unamortized debt issuance costs/debt discount	(9,925)	(17,826)
Short-term debt, net	183,244	152,730
Long-term portion of gross debt	2,848,820	2,961,534
Less: Unamortized debt issuance costs/debt discount	(46,503)	(87,421)
Long-term debt, net	2,802,317	2,874,113
Supplemental information:
Letters of credit	51,574	51,628
Remaining borrowing capacity on revolving credit facility	665,026	818,372
Borrowed federal funds
Debt Instrument [Line Items]
Principal	40,000	20,000
Secured Debt
Debt Instrument [Line Items]
Principal	88,327	85,945
Convertible Debt
Debt Instrument [Line Items]
Principal	310,000	310,000
Unsecured Debt
Debt Instrument [Line Items]
Principal	1,500	0
Revolving Line-of-credit Facility under 2016 Credit Agreement
Debt Instrument [Line Items]
Principal	213,400	0
Line of Credit
Debt Instrument [Line Items]
Principal	40,000	20,000
Line of Credit \| Secured Debt \| 2016 Credit Agreement
Debt Instrument [Line Items]
Principal	2,388,762	2,316,145
Line of Credit \| Secured Debt \| Tranche A Term Loans
Debt Instrument [Line Items]
Principal	953,972	873,777
Line of Credit \| Secured Debt \| Tranche B Term Loans
Debt Instrument [Line Items]
Principal	1,434,790	1,442,368
Notes outstanding \| Senior Notes
Debt Instrument [Line Items]
Principal	$ 0	$ 400,000

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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