| Date | Acquired | Amount |
|---|---|---|
| Mar 24, 2014 | Undisclosed amount | |
| Feb 26, 2013 | Undisclosed amount | |
| Dec 18, 2012 | Undisclosed amount | |
| Nov 16, 2012 | Undisclosed amount | |
| Jul 02, 2012 | $ 2,400,000,000 | |
| May 09, 2012 | Undisclosed amount | |
| Apr 05, 2012 | Undisclosed amount | |
| Apr 02, 2012 | Undisclosed amount | |
| Apr 02, 2012 | Undisclosed amount | |
| Feb 24, 2012 | Undisclosed amount | |
| Sep 13, 2011 | Undisclosed amount | |
| Jun 20, 2011 | Undisclosed amount | |
| Jan 04, 2011 | Undisclosed amount | |
| Dec 22, 2010 | Undisclosed amount | |
| Dec 13, 2010 | $ 820,000,000 | |
| Nov 02, 2010 | Undisclosed amount | |
| Jul 19, 2010 | Undisclosed amount | |
| Jul 01, 2010 | Undisclosed amount | |
| Feb 11, 2010 | Undisclosed amount | |
| Feb 09, 2010 | $ 12,000,000 | |
| Sep 21, 2009 | Undisclosed amount | |
| Feb 13, 2008 | $ 155,000,000 | |
| Dec 21, 2007 | Undisclosed amount | |
| Nov 15, 2007 | Undisclosed amount | |
| Nov 05, 2007 | $ 1,400,000,000 | |
| Aug 02, 2007 | Undisclosed amount | |
| Jul 18, 2007 | Undisclosed amount | |
| Nov 14, 2006 | Undisclosed amount | |
| Mar 22, 2006 | Undisclosed amount | |
| Jan 01, 2000 | Undisclosed amount | |
| Sep 09, 1999 | $ 340,000,000 | |
| Oct 01, 1998 | Undisclosed amount |