Stockholders' Equity and Partners' Capital - Narrative (Details)		1 Months Ended		2 Months Ended	12 Months Ended
	Feb. 14, 2019 $ / shares	Jun. 30, 2018 USD ($) $ / shares	Oct. 31, 2017 shares	Feb. 19, 2019 $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares	Aug. 31, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued on a forward basis (in shares) | shares			2,600,000		2,600,000	2,600,000
Stock issued, value, issued on a forward basis		$ 73,800,000
Stock issued share price (in dollars per share) | $ / shares		$ 28.94
ATM, authorized amount								$ 300,000,000
Remaining amount of common stock available for repurchase					$ 232,800,000
Shares repurchased during period (in shares) | shares					2,600,000
Shares repurchased during period (in dollars per share) | $ / shares					$ 26.12
Stock repurchased during period, value					$ 67,200,000
Restricted Common Stock
Incentive Plan
Granted (in dollars per share) | $ / shares					$ 28.65	$ 29.75	$ 29.82
Fair value of restriction lapsed common stock					$ 7,800,000	$ 5,900,000	$ 5,400,000
Nonvested awards, total compensation cost not yet recognized					$ 7,000,000
Period for recognition (in years)					1 year 3 months 18 days
Restricted Common Stock | General and Administrative Expense
Incentive Plan
Compensation expense					$ 9,800,000	$ 6,900,000	$ 7,100,000
Restricted Common Stock | Minimum
Incentive Plan
Award vesting period (in years)					3 years
Restricted Common Stock | Maximum
Incentive Plan
Award vesting period (in years)					4 years
ATM Offering Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ATM, authorized amount					$ 500,000,000
2006 Incentive Plan
Incentive Plan
Number of shares authorized (in shares) | shares					5,000,000
Number of shares available for grant (in shares) | shares					1,385,001
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares repurchased during period (in shares) | shares				346,000
Shares repurchased during period (in dollars per share) | $ / shares				$ 24.65
Common Stock Dividends
Dividends declared (in dollars per share) | $ / shares	$ 0.310
Healthcare Trust of America Holdings, LP (HTALP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend distribution ratio					1