Fair Value Measurements - Guaranteed Minimum Income Benefit Contracts (Details)	Sep. 30, 2016
Guaranteed Minimum Income Benefit [Member] \| Ceded Credit Risk Secured [Member]
Ceded Credit Risk [Line Items]
GMIB assets percent secured	69.00%

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