Noncontrolling Interests - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($) Entity Property	Dec. 31, 2019 shares
Noncontrolling Interest [Line Items]
Number of third-party joint venture partners (entities) | Entity	5
Number of properties	166
Common OP Unit
Noncontrolling Interest [Line Items]
Conversion of operating partnership units to common stock (in shares) | shares		126,313
Preferred OP Unit
Noncontrolling Interest [Line Items]
Conversion of operating partnership units to common stock (in shares) | shares		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%