Debt - Schedule of Debt (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total Debt		$ 1,979,072	$ 1,362,179
Unamortized Deferred Financing Costs and Premiums/(Discounts)		(9,968)	(8,648)
Debt, net		1,969,104	1,353,531
Derivative, notional amount		$ 850,000	850,000
LIBOR
Debt Instrument [Line Items]
Effective interest rate (percent)		1.69%
2023 Term Loan
Debt Instrument [Line Items]
Effective interest rate (percent)		3.28%
2023 Term Loan | LIBOR
Debt Instrument [Line Items]
Interest rate spread on the variable rate debt (percent)		1.40%
2024 Term Loan
Debt Instrument [Line Items]
Effective interest rate (percent)		3.27%
2024 Term Loan | LIBOR
Debt Instrument [Line Items]
Interest rate spread on the variable rate debt (percent)		1.40%
2026 Term Loan
Debt Instrument [Line Items]
Effective interest rate (percent)		3.59%
2026 Term Loan | LIBOR
Debt Instrument [Line Items]
Interest rate spread on the variable rate debt (percent)		1.75%
Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Total Debt		$ 211,500	0
Effective interest rate (percent)		3.35%
Term of debt instrument		3 years
Extended term on debt		1 year
Revolving Credit Facility | LIBOR | Revolving Credit Facility
Debt Instrument [Line Items]
Interest rate spread on the variable rate debt (percent)		1.45%
Mortgages
Debt Instrument [Line Items]
Total Debt		$ 1,017,572	647,179
Mortgages | HealthSpring Mortgage Loan
Debt Instrument [Line Items]
Total Debt		$ 20,723	21,219
Contractual interest rate on fixed rate debt (percent)		4.18%
Effective interest rate (percent)		4.61%
Mortgages | Midland Mortgage Loan
Debt Instrument [Line Items]
Total Debt		$ 100,249	102,262
Contractual interest rate on fixed rate debt (percent)		3.94%
Effective interest rate (percent)		4.10%
Mortgages | Emporia Partners Mortgage Loan
Debt Instrument [Line Items]
Total Debt		$ 2,104	2,554
Contractual interest rate on fixed rate debt (percent)		5.88%
Effective interest rate (percent)		5.98%
Mortgages | Samsonite
Debt Instrument [Line Items]
Total Debt		$ 21,154	22,085
Contractual interest rate on fixed rate debt (percent)		6.08%
Effective interest rate (percent)		5.14%
Mortgages | Highway 94 loan
Debt Instrument [Line Items]
Total Debt		$ 15,610	16,497
Contractual interest rate on fixed rate debt (percent)		3.75%
Effective interest rate (percent)		4.73%
Mortgages | AIG Loan II
Debt Instrument [Line Items]
Total Debt		$ 126,970	0
Contractual interest rate on fixed rate debt (percent)		4.15%
Effective interest rate (percent)		4.91%
Term of debt instrument		10 years
Mortgages | BOA Loan
Debt Instrument [Line Items]
Total Debt		$ 375,000	375,000
Contractual interest rate on fixed rate debt (percent)		3.77%
Effective interest rate (percent)		3.92%
Mortgages | BOA/KeyBank Loan
Debt Instrument [Line Items]
Total Debt		$ 250,000	0
Contractual interest rate on fixed rate debt (percent)		4.32%
Effective interest rate (percent)		4.16%
Term of debt instrument		10 years
Mortgages | AIG Loan
Debt Instrument [Line Items]
Total Debt		$ 105,762	107,562
Contractual interest rate on fixed rate debt (percent)		4.96%
Effective interest rate (percent)		5.08%
Loans Payable | 2023 Term Loan
Debt Instrument [Line Items]
Total Debt		$ 200,000	0
Term of debt instrument	4 years
Loans Payable | 2024 Term Loan
Debt Instrument [Line Items]
Total Debt		400,000	0
Term of debt instrument	5 years
Loans Payable | 2026 Term Loan
Debt Instrument [Line Items]
Total Debt		150,000	0
Term of debt instrument	7 years
Loans Payable | Term Loan
Debt Instrument [Line Items]
Total Debt		$ 0	$ 715,000
Fixed and Variable Rate Debt
Debt Instrument [Line Items]
Weighted average interest rate of the fixed-rate debt (percent)		3.72%
Fixed Rate Debt
Debt Instrument [Line Items]
Weighted average interest rate of the fixed-rate debt (percent)		3.89%
Interest Rate Swap
Debt Instrument [Line Items]
Derivative, notional amount		$ 425,000