v3.3.1.900
Shareholders' Equity And Net Income Per Share Dividends (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dividends Payable [Line Items]                          
Cash dividends declared per share   $ 0.25 $ 0.25 $ 0.25 $ 0.25 $ 0.25 $ 0.25 $ 0.25 $ 0.25   $ 1 $ 1 $ 0.68
Payments of Cash Dividends   $ 70 $ 71 $ 72 $ 73 $ 73 $ 75 $ 76 $ 77   $ 286 $ 301  
Subsequent Event                          
Dividends Payable [Line Items]                          
Cash dividends declared per share $ 0.29                 $ 1.16