Derivatives - Interest Rate Swap Agreements (Hedging Exposure Future Cash Flows for Forecasted Transactions) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011
Maturity - average period of months	38
Notional Amount	$ 7,400,000
Weighted Average Fixed Interest Rate in Contract	1.86%
12 months or less [Member]
Maturity - lower remaining maturity range	Less than 12 months
Maturity - higher remaining maturity range	Over 12 months
Notional Amount	300,000
Remaining Term in Months	4
Weighted Average Fixed Interest Rate in Contract	3.45%
Over 12 months to 24 months [Member]
Maturity - lower remaining maturity range	12 months
Maturity - higher remaining maturity range	Over 24 months
Notional Amount	800,000
Remaining Term in Months	18
Weighted Average Fixed Interest Rate in Contract	1.90%
Over 24 months to 36 months [Member]
Maturity - lower remaining maturity range	24 months
Maturity - higher remaining maturity range	Over 36 months
Notional Amount	1,200,000
Remaining Term in Months	31
Weighted Average Fixed Interest Rate in Contract	1.90%
Over 36 months to 48 months [Member]
Maturity - lower remaining maturity range	36 months
Maturity - higher remaining maturity range	Over 48 months
Notional Amount	3,800,000
Remaining Term in Months	43
Weighted Average Fixed Interest Rate in Contract	1.78%
Over 48 months to 60 months [Member]
Maturity - lower remaining maturity range	48 months
Maturity - higher remaining maturity range	Over 60 months
Notional Amount	$ 1,300,000
Remaining Term in Months	51
Weighted Average Fixed Interest Rate in Contract	1.65%

Average fixed interest rate related to the group of interest rate derivatives.

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Namespace Prefix:	us-gaap
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The average time remaining until maturity on the group of derivatives identified.

+ Details

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Period Type:	instant

- Definition

The high end of the range of time remaining until maturity when a range is presented for a group of derivatives.

+ Details

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Namespace Prefix:	us-gaap
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	instant

- Definition

The low end of the range of time remaining until maturity when a range is presented for a group of derivatives.

+ Details

Name:	us-gaap_DerivativeLowerRemainingMaturityRange
Namespace Prefix:	us-gaap
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	instant

- Definition

The time remaining until the derivative matures.

+ Details

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Data Type:	us-types:durationStringItemType
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- Definition

Aggregate notional amount of all derivatives designated as cash flow hedging instruments. The notional amount relates to a number of currency units, shares, bushels, pounds, or other units specified in a derivative instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Notional Amount
-URI http://asc.fasb.org/extlink&oid=6519104

+ Details

Name:	us-gaap_NotionalAmountOfCashFlowHedgeInstruments
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant