|
Unsecured Lines Of Credit Payable - Lines Of Credit Unused and Available (Details) (USD $)
|
Dec. 31, 2013
|
Dec. 31, 2012
|
Dec. 31, 2011
|
|---|---|---|---|
| Line of Credit Facility [Line Items] | |||
| Committed capacity | $ 500,000,000 | $ 500,000,000 | $ 475,000,000 |
| Borrowings outstanding | 0 | 0 | 99,000,000 |
|
Credit Facility No. 1 [Member]
|
|||
| Line of Credit Facility [Line Items] | |||
| Committed capacity | 100,000,000 | ||
| Borrowings outstanding | 0 | 0 | |
| Letters of credit issued | 0 | ||
| Unused and available | 100,000,000 | ||
|
Credit Facility No. 2 [Member]
|
|||
| Line of Credit Facility [Line Items] | |||
| Committed capacity | 400,000,000 | ||
| Borrowings outstanding | 0 | 0 | |
| Letters of credit issued | 0 | ||
| Unused and available | $ 400,000,000 |
| X | ||||||||||
|
- Definition
Amount borrowed under the credit facility as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Lines Of Credit Letters Of Credit Issued No definition available.
|