Investments in Real Estate and Real Estate Under Construction - Schedule of Net Real Estate (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments in Real Estate and Real Estate Under Construction [Line Items]
Buildings and building improvements	$ 3,476,022	$ 3,050,082
Land, land estates and land improvements	456,134	472,394
Fixtures and equipment	84	5,577
Construction in progress	4,219	5,119
Real estate - intangible assets	599,091	597,294
Investments in real estate under construction	0	106,652
Real estate, gross	4,535,550	4,237,118
Accumulated depreciation and amortization	(1,225,650)	(1,208,792)
Real estate, net	3,309,900	3,028,326
Accumulated amortization	334,681	363,861
Amortization expense, next 12 months	31,401
Amortization expense, year 2	26,578
Amortization expense, year 3	23,360
Amortization expense, year 4	22,211
Amortization expense, year 5	20,951
Leases, Acquired-in-Place [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Real estate - intangible assets	461,624	436,185
Customer Relationships [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Real estate - intangible assets	97,223	113,839
Above Market Leases [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Real estate - intangible assets	40,244	47,270
LCIF [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Buildings and building improvements	705,565	644,173
Land, land estates and land improvements	88,589	86,120
Fixtures and equipment	84	84
Construction in progress	4	825
Real estate - intangible assets	116,861	104,761
Investments in real estate under construction	0	40,443
Real estate, gross	911,103	876,406
Accumulated depreciation and amortization	(233,121)	(236,930)
Real estate, net	677,982	639,476
Accumulated amortization	54,745	54,425
Amortization expense, next 12 months	5,307
Amortization expense, year 2	4,557
Amortization expense, year 3	4,445
Amortization expense, year 4	4,431
Amortization expense, year 5	4,431
LCIF [Member] | Leases, Acquired-in-Place [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Real estate - intangible assets	95,166	82,190
LCIF [Member] | Customer Relationships [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Real estate - intangible assets	19,067	19,943
LCIF [Member] | Above Market Leases [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Real estate - intangible assets	$ 2,628	$ 2,628