Subsequent Events Debt Issuance (Details) (3.5% Senior Notes due January 2025, Subsequent Event, USD $)	0 Months Ended
Jan. 29, 2015	Jan. 29, 2015
3.5% Senior Notes due January 2025 \| Subsequent Event
Subsequent Event [Line Items]
Principal value	$ 350,000,000	$ 350,000,000
Proceeds from issuance of senior notes, net of discount and issuance cost	$ 346,400,000

Face (par) amount of debt instrument at time of issuance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

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