Debt - Narrative (Details) - USD ($)	3 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Mar. 26, 2021	Jul. 10, 2020
Debt Instrument [Line Items]
Long-term debt	$ 694,800,000		$ 694,500,000
Letters of credit issued	5,400,000
Interest costs	10,300,000	$ 9,500,000
Interest costs, capitalized	100,000	2,800,000
Debt prepayment costs	0	(8,200,000)
Interest Rate Swaps | Fair value hedging
Debt Instrument [Line Items]
Derivative, gain on derivative	$ 2,300,000	2,300,000
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Current borrowing capacity				$ 300,000,000
Debt instrument, covenant, credit commitment amount				300,000,000
Maximum borrowing capacity				500,000,000
Commitment fee rate	0.35%
Short-term credit agreement borrowings	$ 0
Credit Agreement available for future borrowings	$ 294,600,000
Borrowing rate	2.08%
Required interest coverage ratio one	3.00
Required interest coverage ratio two	3.50
Minimum available liquidity	$ 150,000,000
Asset coverage ratio	1.10
Revolving Credit Facility | Line of Credit | LIBOR
Debt Instrument [Line Items]
Interest rate margin	2.00%
Revolving Credit Facility | Line of Credit | Base Rate
Debt Instrument [Line Items]
Interest rate margin	1.00%
Revolving Credit Facility | Line of Credit | Minimum
Debt Instrument [Line Items]
Commitment fee rate	0.275%
Revolving Credit Facility | Line of Credit | Minimum | LIBOR
Debt Instrument [Line Items]
Interest rate margin	1.25%
Revolving Credit Facility | Line of Credit | Minimum | Base Rate
Debt Instrument [Line Items]
Interest rate margin	0.25%
Revolving Credit Facility | Line of Credit | Maximum
Debt Instrument [Line Items]
Commitment fee rate	0.375%
Required debt to capital ratio (less than)	0.55
Revolving Credit Facility | Line of Credit | Maximum | LIBOR
Debt Instrument [Line Items]
Interest rate margin	2.25%
Revolving Credit Facility | Line of Credit | Maximum | Base Rate
Debt Instrument [Line Items]
Interest rate margin	1.25%
Letters of credit | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 40,000,000
Letter of credit fees	2.00%
Letters of credit | Line of Credit | Minimum
Debt Instrument [Line Items]
Letter of credit fees	1.25%
Letters of credit | Line of Credit | Maximum
Debt Instrument [Line Items]
Letter of credit fees	2.25%
Senior unsecured notes, 6.375% due July 2028
Debt Instrument [Line Items]
Face amount	$ 400,000,000		$ 400,000,000		$ 400,000,000
Interest rate	6.375%		6.375%		6.375%
Long-term debt	$ 395,200,000		$ 395,000,000.0
Senior unsecured notes, 5.20% due July 2021
Debt Instrument [Line Items]
Face amount					$ 250,000,000
Debt prepayment costs	0	$ 10,500,000
Senior unsecured notes, 4.45% due March 2023
Debt Instrument [Line Items]
Face amount	$ 300,000,000		$ 300,000,000
Interest rate	4.45%		4.45%	4.45%
Long-term debt	$ 299,600,000		$ 299,500,000	$ 300,000,000