Acquisitions (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended		24 Months Ended
	Jun. 30, 2017 USD ($) item	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) item	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) ft² item	Dec. 31, 2015 USD ($) ft² property item	Dec. 31, 2016 USD ($) ft² item
Acquisitions
Properties, net	$ 1,960,498		$ 1,960,498		$ 1,944,720		$ 1,944,720
Liabilities assumed:
Revenues	211,569	$ 199,992	410,289	$ 395,485
Net income (loss)	123,233	112,071	226,087	139,117
Bargain purchase gains				8,406
Depreciation and amortization			42,701	34,664
Gain (loss) on derivative financial instruments, net	(37,586)	$ 20,253	(41,935)	$ (4,465)
Goodwill	$ 140,437		$ 140,437		$ 140,437		$ 140,437
Medical Office Portfolio
Acquisitions
Area of property | ft²					1,900,000		1,900,000
Number of acquired properties closed | item					34
Purchase price					$ 758,800
Liabilities assumed:
Bargain purchase gains					0
Goodwill					$ 0		$ 0
Woodstar Portfolio
Acquisitions
Number of properties in portfolio investment | item	32		32
Number of acquired properties closed | item					14	18	32
Number of units acquired | item			8,948
Purchase price							$ 421,500
Liabilities assumed:
Bargain purchase gains					$ 8,400
Goodwill					0		$ 0
Ireland Portfolio
Acquisitions
Area of property | ft²						600,000
Debt incurred to fund acquisition						$ 328,600
Number of properties sold | item	1		1
Proceeds from sale of property	$ 3,900		$ 3,900
Assets acquired:
Total assets acquired						518,200
Liabilities assumed:
Total liabilities assumed						283,000
Bargain purchase gains						0
Goodwill						$ 0
REO Portfolio
Assets acquired:
Properties	18,301		18,301
Intangible assets	1,917		1,917
Other assets	1		1
Total assets acquired	20,219		20,219
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	567		567
Total liabilities assumed	567		567
Net assets acquired	19,652		19,652
REO Portfolio | ASU 2015-16
Assets acquired:
Properties	12,747		12,747
Intangible assets	3,468		3,468
Other assets	97		97
Total assets acquired	16,312		16,312
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	1,397		1,397
Total liabilities assumed	1,397		1,397
Non-controlling interests	3,084		3,084
Net assets acquired	11,831		11,831
REO Portfolio | ASU 2015-16 | Initial Amount
Assets acquired:
Properties	12,087		12,087
Intangible assets	4,270		4,270
Other assets	97		97
Total assets acquired	16,454		16,454
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	1,539		1,539
Total liabilities assumed	1,539		1,539
Non-controlling interests	3,084		3,084
Net assets acquired	11,831		11,831
REO Portfolio | ASU 2015-16 | Measurement Period Adjustments
Assets acquired:
Properties	660		660
Intangible assets	(802)		(802)
Total assets acquired	(142)		(142)
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	(142)		(142)
Total liabilities assumed	(142)		(142)
Net Leased Office Property | Ireland Portfolio
Acquisitions
Number of properties in portfolio investment | property						12
Multifamily Property | Ireland Portfolio
Acquisitions
Number of properties in portfolio investment | property						1
Investment and Servicing Segment
Acquisitions
Properties, net	$ 19,000		$ 19,000
Number of real estate business acquired | item							24
Purchase price							$ 268,500
Number of properties sold | item	2		2
Proceeds from sale of property	$ 14,700		$ 14,700
Gain on sale of property	5,100		5,100
Liabilities assumed:
Bargain purchase gains	600		600		$ 8,800
Goodwill	$ 0		$ 0