Corporate Office Relocation (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Expected restructuring and relocation costs	$ 10.0
Home Office Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance, retention, relocation, and related costs	4.4	$ 16.3	$ 15.4
Home Office Relocation [Member] \| Employee severance, retention, and relocation costs [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance, retention, relocation, and related costs	2.0	7.6	15.0
Home Office Relocation [Member] \| Asset impairments [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance, retention, relocation, and related costs	$ 2.3	$ 8.7	$ 0.4

Discloses the amount charged against the accrued restructuring reserves, or earnings if not previously accrued, during the period for the specified type of restructuring cost.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section P
-Subsection 3, 4

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