Debt - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) contract	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) contract	Sep. 30, 2020 USD ($)
Schedule of Debt Instruments [Line Items]
Interest paid	$ 16,200,000	$ 12,800,000	$ 41,500,000	$ 41,800,000
Interest costs capitalized	$ 1,000,000	$ 200,000	$ 2,700,000	$ 600,000
Forward starting interest rate swaps
Schedule of Debt Instruments [Line Items]
Number of swap agreements | contract	1		1
Notional amount of interest rate swap agreements	$ 50,000,000		$ 50,000,000
Gain on settlement of interest rate swap agreement	600,000		600,000
$300 Million Unsecured Senior Notes due 2032 | Unsecured Debt
Schedule of Debt Instruments [Line Items]
Face amount of debt instrument	$ 300,000,000		$ 300,000,000
Stated rate (percent)	2.75%		2.75%
Proceeds from issuance of debt			$ 298,500,000
Debt instrument, discount	$ 1,500,000		$ 1,500,000
Debt instrument, term			10 years 6 months
Debt instrument, redemption price, percentage			100.00%
Amended and Restated $300 Million Unsecured 2011 Term Loan | Unsecured Debt
Schedule of Debt Instruments [Line Items]
Face amount of debt instrument	$ 300,000,000		$ 300,000,000