Junior Subordinated Debentures - Payments and other disclosures (Details) $ in Millions		12 Months Ended
Apr. 21, 2014 USD ($)	Dec. 31, 2015 item
Junior subordinated debentures
Payments to indentured trustees \| $	$ 19.7
Junior subordinated debentures
Junior subordinated debentures
Period of interest payments that may be deferred (in quarters) \| item		20

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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