Stock Holders Equity Cash Dividends (Details) - USD ($) $ / shares in Units, $ in Millions					12 Months Ended
Jul. 31, 2018	May 01, 2018	Jan. 30, 2018	Oct. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Quarterly cash dividend per share	$ 0.06	$ 0.06	$ 0.05	$ 0.05
Cash dividend paid	$ 6.6	$ 6.5	$ 5.4	$ 5.5	$ 24.0	$ 10.9

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

Reference 1: 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=27012166&loc=d3e187085-122770

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