Subsequent events (Details) - Subsequent event - Carl J. Williams	Feb. 02, 2016
Subsequent events
Term of renewal	1 year
Period of base salary as severance	12 years
Period of health benefit continuation	12 years
Period Of Base Salary Paid At Change Of Control	6 months

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