Income Taxes, Valuation Allowance (Details) (New Markets Tax Credit Carryforward [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
New Markets Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards, Deferred Tax Asset	$ 95.7	$ 95.4
Tax Credit Carryforward, Valuation Allowance	$ 0

Amount of valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from tax credit carryforwards for which it is more likely than not that a tax benefit will not be realized.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Valuation Allowance

-URI http://asc.fasb.org/extlink&oid=6528051

Name:	us-gaap_TaxCreditCarryforwardValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant