Noncontrolling Interest in Operating Partnership and Other Noncontrolling Interests - Schedule of OP Unit Activity (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Noncontrolling Interest [Abstract]
OP Units redeemed for common stock (in shares)	0	5,000
OP Units redeemed for cash (in shares)	13,028	0
Cash paid for OP Units redeemed	$ 2,672	$ 0

Noncontrolling Interest, Operating Partnership Units Redeemed For Common Stock

No definition available.

Name:	exr_NoncontrollingInterestOperatingPartnershipUnitsRedeemedForCommonStock
Namespace Prefix:	exr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration