Financing arrangements (Master Repurchase Agreement) (Details) - Master Repurchase Agreement obligation due 2018 [Member] $ in Billions	Sep. 30, 2013 USD ($)
Debt Instrument [Line Items]
Loans payable to bank, noncurrent	$ 3.1
LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.10%

Carrying value as of the balance sheet date of loans from a bank with maturities initially due after one year or beyond the operating cycle if longer, excluding current portion.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 22
-Article 5

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