Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Name:	us-gaap_TreasuryStockValueAcquiredCostMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Treasury Stock - Schedule of repurchase of common stock (Details) - USD ($) $ in Millions	3 Months Ended	41 Months Ended
	Aug. 31, 2021	Aug. 31, 2021	May 31, 2021	Mar. 31, 2020	Mar. 18, 2020	Mar. 21, 2018
Stockholders' Equity Attributable to Parent [Abstract]
Authorized amount of stock to be repurchased			$ 100.0	$ 50.0	$ 50.0	$ 50.0
Total current Board authorizations		$ (32.7)
Less repurchases made under these authorizations	$ 67.3	$ 67.3
Number of common stock repurchased (in shares)	0