Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) segment shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 32,713,000	$ 126,221,000
Restricted cash	4,903,000	7,309,000
Total cash, cash equivalents and restricted cash	$ 37,616,000	133,530,000	$ 118,560,000	$ 25,045,000
Assets Held-for-sale [Abstract]
Assets held-for-sale, period of sale	1 year
Real estate investments:
Impairment	$ 0	8,887,000	13,922,000
Impairment of real estate notes receivable	$ 0	$ 0	0
Investment in unconsolidated joint ventures, ownership percentage	50.00%	50.00%
Investment in unconsolidated joint venture	$ 65,888,000	$ 67,172,000
Income (loss) from unconsolidated joint venture	1,882,000	1,735,000	782,000
Noncontrolling Interest [Abstract]
Redeemable noncontrolling interests	0	6,544,000	6,737,000
Income Taxes [Abstract]
Tax basis in excess of carrying amount on real estate assets	606,600,000
Concentration of Credit Risk [Abstract]
Cash balances in excess of FDIC insured limits	$ 39,800,000
Segment Reporting [Abstract]
Number of reportable segments | segment	1
Recently Issued or Adopted Accounting Pronouncements [Abstract]
General and administrative	$ 41,360,000	35,196,000	33,403,000
ASU 2016-02
Recently Issued or Adopted Accounting Pronouncements [Abstract]
General and administrative		4,900,000
ASU 2018-20
Recently Issued or Adopted Accounting Pronouncements [Abstract]
Lessor, variable payments		13,900,000
Maximum
Leases [Abstract]
Lessor, term of contract	7 years
Minimum
Leases [Abstract]
Lessor, term of contract	3 years
Buildings | Maximum
Property, Plant and Equipment [Abstract]
Property, plant and equipment, useful life	39 years
Tenant Improvements | Maximum
Property, Plant and Equipment [Abstract]
Life on which building depreciation in income statement is computed	10 years
Tenant Improvements | Minimum
Property, Plant and Equipment [Abstract]
Life on which building depreciation in income statement is computed	1 year
Furniture, fixtures and equipment
Property, Plant and Equipment [Abstract]
Life on which building depreciation in income statement is computed	5 years
Building and Building Improvements
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 219,200,000	$ 202,800,000	$ 172,600,000
Healthcare Trust of America Holdings, LP (HTALP)
Partners' Capital Notes [Abstract]
Limited partner's capital, units issued (in shares) | shares	3,834,279	3,929,083	4,100,000
Limited partner's capital, units outstanding (in shares) | shares	3,834,279	3,929,083	4,100,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 32,713,000	$ 126,221,000	$ 100,356,000
Restricted cash	4,903,000	7,309,000	18,204,000
Total cash, cash equivalents and restricted cash	37,616,000	133,530,000	118,560,000	$ 25,045,000
Real estate investments:
Impairment	0	8,887,000	13,922,000
Investment in unconsolidated joint venture	65,888,000	67,172,000
Income (loss) from unconsolidated joint venture	1,882,000	1,735,000	782,000
Noncontrolling Interest [Abstract]
Redeemable noncontrolling interests	0	6,544,000
Recently Issued or Adopted Accounting Pronouncements [Abstract]
General and administrative	$ 41,360,000	$ 35,196,000	$ 33,403,000