Aggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

Name:	us-gaap_NotionalAmountOfInterestRateDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Derivatives and Hedging (Details) (Interest Rate Swap, USD $) In Millions, unless otherwise specified		12 Months Ended		12 Months Ended
	Jun. 30, 2007 Derivative_Agreement	Dec. 31, 2012 Interest Rate Swap 1	Mar. 31, 2010 Interest Rate Swap 1	Dec. 31, 2012 Interst Rate Swap 2	Mar. 31, 2011 Interst Rate Swap 2
Derivative [Line Items]
Number of interest rate swap agreements	2
Number of years in term for interest rate swap agreements		3 years		4 years
Fixed LIBOR base rate			4.91%		4.935%
Notional amount of interest rate derivatives			$ 20		$ 20