Redemption of preferred stock (Details 2)	Apr. 02, 2017 USD ($)
Stockholders' Equity Note [Abstract]
Redeemable preferred stock classified as long term debt	$ 300,000
Payments for repurchase of redeemable preferred stock	$ 15,900,000

The cash outflow for reacquisition of callable preferred stock.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

Name:	us-gaap_PaymentsForRepurchaseOfRedeemablePreferredStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration