Subsequent Events - Sale of Building (Details) $ in Millions	3 Months Ended
Dec. 31, 2018 USD ($)
Forecast \| Minnetonka, MN
Subsequent Event [Line Items]
Proceeds from sale of buildings	$ 10.0

The cash inflow from sale of buildings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

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