Basis of Presentation and Significant Accounting Policies Commercial Real Estate Assets (of Discontinued Operations) (Details)	12 Months Ended
Dec. 31, 2017
Basis of Presentation and Significant Accounting Policies [Abstract]
Threshold period when loans are considered past due	30 days
Threshold period when delinquent loans are placed on nonaccrual status	60 days

Threshold period for when financing receivable is considered past due, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Excludes threshold period past due to write off as uncollectible.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447

Name:	us-gaap_FinancingReceivableThresholdPeriodPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant