Derivative and Other Fair Value Instruments - Additional Information (Details)	1 Months Ended					12 Months Ended
	Apr. 30, 2020 USD ($) DerivativeInstrument	Jul. 31, 2019 USD ($) DerivativeInstrument	Jun. 30, 2019 USD ($) DerivativeInstrument	Nov. 30, 2018 USD ($) DerivativeInstrument	Feb. 28, 2018 USD ($) DerivativeInstrument	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Derivative [Line Items]
Unrealized gain (loss) on interest rate cash flow hedges, pretax, accumulated other comprehensive income (loss)						$ 43,700,000	$ 77,600,000
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net						10,200,000
Number of interest rate swaps matured | DerivativeInstrument		6
Repayments of unsecured debt						$ 750,000,000	$ 1,050,000,000
Forward Starting Swaps [Member]
Derivative [Line Items]
Payments for settlement of derivative instruments	$ 1,200,000
Forward starting swaps settled | DerivativeInstrument	2		10	6	2
Debt instrument face amount			$ 600,000,000.0	$ 400,000,000.0	$ 500,000,000.0
Increase (decrease) in charges hedge termination activities	$ 1,200,000		41,600,000	(16,500,000)	(1,600,000)
Mortgage notes period	5 years
Proceeds from settlement of derivative instruments			41,800,000	16,400,000	$ 1,600,000
Interest expense			$ 200,000	$ 120,000
Debt instrument, term			10 years	10 years	10 years
2.375% Notes [Member]
Derivative [Line Items]
Repayments of unsecured debt		$ 450,000,000.0
Debt instrument, interest rate, stated percentage		2.375%
Mortgages [Member] | Forward Starting Swaps [Member]
Derivative [Line Items]
Debt instrument face amount	$ 495,000,000.0
Secured conventional mortgage notes period	10 years