Senior Unsecured Notes (Summary Of Senior Unsecured Notes) (Details) - USD ($)
$ in Thousands |
6 Months Ended |
|
Jun. 30, 2015 |
Dec. 31, 2014 |
| Debt Instrument [Line Items] |
|
|
|
| Senior Unsecured Notes |
|
$ 1,268,293
|
$ 1,267,744
|
| 5.800% Senior Unsecured Notes, Due January 15, 2016 [Member] |
|
|
|
| Debt Instrument [Line Items] |
|
|
|
| Senior Unsecured Notes |
|
$ 200,047
|
200,086
|
| Effective rate |
[1] |
5.806%
|
|
| Interest rate of senior unsecured notes |
|
5.80%
|
|
| Maturity date of the senior unsecured notes |
|
Jan. 15, 2016
|
|
| 2.500% Senior Unsecured Notes Due December 15, 2017 [Member] |
|
|
|
| Debt Instrument [Line Items] |
|
|
|
| Senior Unsecured Notes |
|
$ 249,298
|
249,150
|
| Effective rate |
[1] |
2.803%
|
|
| Interest rate of senior unsecured notes |
|
2.50%
|
|
| Maturity date of the senior unsecured notes |
|
Dec. 15, 2017
|
|
| 7.750% Senior Unsecured Notes, Due August 15, 2019 [Member] |
|
|
|
| Debt Instrument [Line Items] |
|
|
|
| Senior Unsecured Notes |
|
$ 249,120
|
249,013
|
| Effective rate |
[1] |
8.017%
|
|
| Interest rate of senior unsecured notes |
|
7.75%
|
|
| Maturity date of the senior unsecured notes |
|
Aug. 15, 2019
|
|
| 4.500% Senior Unsecured Notes Due April 18, 2022 [Member] |
|
|
|
| Debt Instrument [Line Items] |
|
|
|
| Senior Unsecured Notes |
|
$ 299,595
|
299,565
|
| Effective rate |
[1] |
4.612%
|
|
| Interest rate of senior unsecured notes |
|
4.50%
|
|
| Maturity date of the senior unsecured notes |
|
Apr. 18, 2022
|
|
| 3.150% Senior Unsecured Notes, Due May 15, 2023 [Member] |
|
|
|
| Debt Instrument [Line Items] |
|
|
|
| Senior Unsecured Notes |
|
$ 270,233
|
$ 269,930
|
| Effective rate |
[1] |
3.517%
|
|
| Interest rate of senior unsecured notes |
|
3.15%
|
|
| Maturity date of the senior unsecured notes |
|
May 15, 2023
|
|
|
|