Debt - Narrative (Details) - Line of Credit Facility - USD ($) $ in Millions			3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Jun. 18, 2020	Jun. 17, 2020
Fair Value, Inputs, Level 2
Line of Credit Facility [Line Items]
Interest rate cash flow hedge liability at fair value	$ 8.3	$ 8.3	$ 8.3		$ 8.3		$ 4.6
Interest Rate Swap
Line of Credit Facility [Line Items]
Derivative liability, notional amount	$ 200.0	$ 200.0	$ 200.0		$ 200.0
Derivative, fixed interest rate	2.70%	2.70%	2.70%		2.70%
Debt instrument, description of variable rate basis					one-month LIBOR
Variable interest rate	0.20%	0.20%	0.20%		0.20%
Maximum | Interest Rate Swap
Line of Credit Facility [Line Items]
Derivative, maturity date					Jun. 30, 2022
Other liabilities
Line of Credit Facility [Line Items]
Derivative liability	$ 8.3	$ 8.3	$ 8.3		$ 8.3		$ 4.6
Revolving credit facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	500.0	500.0	500.0		500.0
Commitment fee for unused commitments			0.3	$ 0.3	$ 0.6	$ 0.7
Credit facility, expiration date					Nov. 18, 2024		Nov. 18, 2024
Revolving credit facility | Long-term debt
Line of Credit Facility [Line Items]
Credit facility, outstanding amount	0.0	0.0	0.0		$ 0.0
Letter of credit sublimit to revolving credit facility
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	1.6	1.6	1.6		1.6
Letter of credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	78.0	78.0	78.0		78.0
Letters of credit outstanding, amount	71.0	$ 71.0	71.0		71.0
AR Facility
Line of Credit Facility [Line Items]
Credit facility, expiration date		Jun. 30, 2022
AR Facility | Short-term debt
Line of Credit Facility [Line Items]
Credit facility, outstanding amount	0.0	$ 0.0	0.0		0.0		$ 105.0
Line of credit facility, remaining borrowing capacity	$ 0.0	$ 0.0	0.0		0.0
Repurchase facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity								$ 80.0
Credit facility, expiration date	Jun. 29, 2021	Jun. 29, 2021
Repurchase facility | Short-term debt
Line of Credit Facility [Line Items]
Maximum borrowing capacity									$ 90.0
Credit facility, outstanding amount	$ 80.0	$ 80.0	$ 80.0		$ 80.0		$ 90.0
Borrowing rate	1.90%	1.90%	1.90%		1.90%
Line of credit facility, remaining borrowing capacity	$ 0.0	$ 0.0	$ 0.0		$ 0.0
AR securitization facilities | Maximum
Line of Credit Facility [Line Items]
Debt instrument, collateral amount	$ 237.9	$ 237.9	$ 237.9		$ 237.9