Investments Low Income Housing Tax Credits (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Investments, All Other Investments [Abstract]
Low Income Housing Tax Credits	$ 9.4	$ 10.4
Amortization of Low Income Housing Investments	(6.8)	(7.0)
Tax Benefits from Low Income Housing Investments	$ 2.6	$ 3.4

The amount deducted from an entities' taxes, reflecting a percentage of an amount invested in certain assets spread over the useful life of those assets; includes deferred investment tax credits.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Name:	us-gaap_InvestmentTaxCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration