COMMON STOCK - Treasury Stock (Narrative) (Details) - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 30, 2016	Jul. 31, 2014
Treasury Stock
Aggregate cost of stock repurchases	$ 662,300,000	$ 280,100,000	$ 300,900,000
Treasury Stock
Treasury Stock
Shares repurchased (in shares)	7.3	2.6	4.4
Aggregate cost of stock repurchases	$ 662,300,000	$ 280,100,000	$ 300,900,000
July 2014
Treasury Stock
Authorized amount for share repurchase					$ 750,000,000.0
November 2016
Treasury Stock
Authorized amount for share repurchase				$ 1,000,000,000.0