Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Subsequent events (Details) - USD ($) $ in Millions	Nov. 01, 2016	Aug. 02, 2016	Dec. 31, 2015	Dec. 31, 2014
Subsequent events
Shares repurchased, authorized amount		$ 6.0	$ 13.5	$ 13.5
Subsequent event
Subsequent events
Shares repurchased, authorized amount	$ 10.0