| Date | Acquired | Amount |
|---|---|---|
| Oct 17, 2017 |
|
$ 1,000,000,000 |
| Jul 08, 2016 |
|
$ 2,000,000,000 |
| May 23, 2016 |
|
$ 643,000,000 |
| Sep 10, 2015 |
|
$ 1,000,000,000 |
| Oct 23, 2014 |
|
$ 840,000,000 |
| Mar 31, 2014 |
|
$ 352,000,000 |
