Shareholders' Equity - Stock Repurchase (Details) - October 2015 Stock Repurchase Program - USD ($) shares in Millions	3 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Total amount of treasury stock repurchased	$ 500,000,000
Treasury stock, shares, acquired (in shares)	0.7	0.6	2.8
Treasury stock, acquired	$ 50,000,000	$ 50,000,000	$ 200,000,000	$ 200,000,000