Financial Instruments and Fair Values - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap agreements liability	$ 11,629,000		$ 11,629,000		$ 13,330,000
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap agreements liability	11,700,000		11,700,000
Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate notional value	265,000,000.0		265,000,000.0		390,000,000.0
Net unrealized gain (loss)	600,000	$ (12,200,000)	(16,300,000)	$ (19,400,000)
Net loss to be reclassified into interest expense within the next 12 months			(11,500,000)
Accounts payable and accrued expenses | Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap agreements liability	11,600,000		11,600,000		$ 13,300,000
LIBOR | Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap, Three Month LIBOR, 2.9580%
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	125,000,000.0		$ 125,000,000.0
Payment of termination settlement fee	$ 20,300,000