Noncontrolling Interests - Narrative (Details) $ in Millions	2 Months Ended	6 Months Ended	12 Months Ended
	Feb. 29, 2020 USD ($)	Jun. 30, 2020 Joint_Venture Entity Property shares	Dec. 31, 2019 shares
Noncontrolling Interest [Line Items]
Number of third-party joint venture partners (entities) | Joint_Venture		5
Number of properties		166
Common OP Unit
Noncontrolling Interest [Line Items]
Conversion of operating partnership units to common stock (in shares) | shares		0	126,313
Preferred OP Unit
Noncontrolling Interest [Line Items]
Conversion of operating partnership units to common stock (in shares) | shares		0	42,271
Core Transaction
Noncontrolling Interest [Line Items]
Number of properties		5
Change in fair value of redeemable noncontrolling interest | $	$ 77.2
Core Transaction | Core Joint Ventures
Noncontrolling Interest [Line Items]
Ownership percentage		100.00%
In-process development properties
Noncontrolling Interest [Line Items]
Number of properties		10
AMERICAN CAMPUS COMMUNITIES OPERATING PARTNERSHIP LP
Noncontrolling Interest [Line Items]
Number of third-party joint venture partners (entities) | Entity		4
AMERICAN CAMPUS COMMUNITIES OPERATING PARTNERSHIP LP | Operating Partnership
Noncontrolling Interest [Line Items]
Equity interests held by owners of common units and preferred units (percent)		0.40%	0.40%