Carrying value as of the balance sheet date of the sum of the obligations to contract holders to provide to them an agreed upon rate of return pursuant to the terms of the underlying contract. These contracts represent lending by the contract holders to the entity in return for a guaranteed (primarily fixed) interest rate until maturity, unless called earlier if the contracts provide that option to the contract holders (usually institutions). There is little or no insurance risk for the entity.

Name:	us-gaap_BorrowingsUnderGuaranteedInvestmentAgreements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Financing and Other Debt - Narrative (Details)				3 Months Ended		9 Months Ended		12 Months Ended
Financing and Other Debt - Narrative (Details)	Apr. 01, 2021 USD ($)	Mar. 15, 2021 USD ($)	Jul. 01, 2020 USD ($) trading_day $ / shares shares	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Jan. 01, 2021 USD ($)
Debt Instrument [Line Items]
Long-term debt				$ 3,041,989,000		$ 3,041,989,000		$ 3,132,090,000
Letters of credit				51,574,000		51,574,000		51,628,000
Gain (loss) on extinguishment of debt						3,400,000
General and administrative expenses incurred						5,500,000
Less: Unamortized issuance cost				16,100,000		16,100,000
Redemption price		$ 400,000,000
Operating interest						1,400,000
Proceeds from issuance of convertible notes						0	$ 299,150,000
Borrowings under guaranteed investment agreements				61,500,000		61,500,000		61,500,000
Long-term debt, net										$ 2,874,113,000
Pledged receivables held as collateral				378,700,000		378,700,000
Private Placement \| Common Stock Issued
Debt Instrument [Line Items]
Sale of stock, number of shares Issued in transaction (in shares) \| shares			577,254
Sale of stock, consideration received on transaction			$ 90,000,000
Sale of stock, price per share ( in dollars per share) \| $ / shares			$ 155.91
Secured Debt
Debt Instrument [Line Items]
Long-term debt				88,327,000		88,327,000		85,945,000
Line of Credit
Debt Instrument [Line Items]
Remaining borrowing capacity on revolving credit facility				561,000,000		561,000,000		376,000,000
Convertible Debt
Debt Instrument [Line Items]
Long-term debt				$ 310,000,000		$ 310,000,000		$ 310,000,000
Proceeds from issuance of convertible notes			$ 389,200,000
2016 Credit Agreement
Debt Instrument [Line Items]
Weighted average effective interest rate (as a percent)				2.20%		2.20%		2.30%
Commitment fee percentage						0.40%		0.40%
2016 Credit Agreement \| Minimum
Debt Instrument [Line Items]
Commitment fee percentage						0.25%
2016 Credit Agreement \| Maximum
Debt Instrument [Line Items]
Commitment fee percentage						0.50%
Convertible Senior Notes Due 2027 \| Convertible Debt
Debt Instrument [Line Items]
Aggregate amount			310,000,000
Long-term debt				$ 310,000,000		$ 310,000,000		$ 310,000,000
Operating interest				$ 5,550,000	$ 6,656,000	$ 16,679,000	$ 6,656,000
Proceeds from issuance of convertible notes			$ 299,200,000
Debt instrument, term			7 years
Interest rate, stated percentage			6.50%	0.065%		0.065%
Conversion price (in dollars per share) \| $ / shares			$ 200
Threshold percentage			200.00%
Number trading days \| trading_day			20
Number of consecutive trading days \| trading_day			30
Redemption price, percent			105.00%
Effective interest rate on the liability component				7.50%		7.50%
Long-term debt, net				$ 294,568,000		$ 294,568,000		$ 240,887,000
Convertible Senior Notes Due 2027 \| Convertible Debt \| Minimum
Debt Instrument [Line Items]
Number trading days \| trading_day			5
Australian Securitization Facility
Debt Instrument [Line Items]
Interest rate during period, percent						0.91%		0.97%
Short-term debt, net				59,600,000		$ 59,600,000		$ 62,600,000
European Securitization Facility
Debt Instrument [Line Items]
Interest rate during period, percent						1.04%		0.98%
Securitized debt				28,700,000		$ 28,700,000		$ 23,400,000
Revolving Line-of-credit Facility under 2016 Credit Agreement
Debt Instrument [Line Items]
Long-term debt				213,400,000		213,400,000		0
Revolving Line-of-credit Facility under 2016 Credit Agreement \| Federal Reserve Bank
Debt Instrument [Line Items]
Letters of credit				0		0		0
Current borrowing capacity				277,200,000		277,200,000
Revolving Line-of-credit Facility under 2016 Credit Agreement \| Minimum \| Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent	0.75%
Revolving Line-of-credit Facility under 2016 Credit Agreement \| 2016 Credit Agreement
Debt Instrument [Line Items]
Remaining borrowing capacity on revolving credit facility	$ 930,000,000								$ 870,000,000
Line of Credit
Debt Instrument [Line Items]
Long-term debt				40,000,000		40,000,000		20,000,000
Line of Credit \| 2016 Credit Agreement \| Secured Debt
Debt Instrument [Line Items]
Long-term debt				2,388,762,000		2,388,762,000		2,316,145,000
Line of Credit \| Tranche A Term Loans \| Secured Debt
Debt Instrument [Line Items]
Aggregate amount	978,400,000
Long-term debt				953,972,000		953,972,000		873,777,000
Line of Credit \| Tranche B Term Loans \| Secured Debt
Debt Instrument [Line Items]
Aggregate amount	$ 1,442,000,000
Long-term debt				1,434,790,000		1,434,790,000		1,442,368,000
Credit Facility Term Loans \| 2016 Credit Agreement \| Minimum
Debt Instrument [Line Items]
Consolidated leverage ratio	7.50
Credit Facility Term Loans \| 2016 Credit Agreement \| Maximum
Debt Instrument [Line Items]
Consolidated leverage ratio	6.25
Credit Facility Term Loans \| Tranche A Term Loans
Debt Instrument [Line Items]
Line of credit facility, periodic payment	$ 12,200,000
Credit Facility Term Loans \| Tranche B Term Loans
Debt Instrument [Line Items]
Line of credit facility, periodic payment	$ 3,600,000
Credit Facility Term Loans \| Tranche B Term Loans \| Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent	2.25%
Credit Facility Term Loans \| Tranche B Term Loans \| Base Rate
Debt Instrument [Line Items]
Margin on variable rate, percent	1.25%
Notes outstanding \| Senior Notes
Debt Instrument [Line Items]
Long-term debt				$ 0		$ 0		400,000,000
Long-term deposits		$ 400,000,000
Participation Debt \| Line of Credit
Debt Instrument [Line Items]
Weighted average effective interest rate (as a percent)				2.36%		2.36%
Long-term debt, net				$ 1,500,000		$ 1,500,000		$ 0
Participation Debt \| Line of Credit \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Margin on variable rate, percent						2.25%
Participation Debt \| Line of Credit \| Maximum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Margin on variable rate, percent						2.50%