Statutory Requirements of Bonds Deposited with Insurance Regulatory Authorities (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Regulatory Capital Requirements [Abstract]
Assets held by insurance regulators	$ 16

Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 320

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6485772&loc=d3e22002-158495

Name:	us-gaap_AssetsHeldByInsuranceRegulators
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant