Indebtedness (Senior Notes Narrative) (Details) - Jun. 30, 2015 - Senior notes, net [Member] - USD ($) $ in Millions	Total
3.25% senior notes due October 2015 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 250
Debt instrument, interest rate, stated percentage	3.25%
2.95% senior notes due June 2016 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 250
Debt instrument, interest rate, stated percentage	2.95%

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 55

-Paragraph 8

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

Reference 2: 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

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