Basis of Presentation and Significant Events - Narrative (Details)		9 Months Ended
	Jul. 02, 2015 USD ($) $ / shares shares	Sep. 30, 2015 Segment
Subsequent Event [Line Items]
Maximum dividend allowed prior to merger | $ / shares	$ 0.29
Number of reportable segments | Segment		3
Agreement and Plan of Merger with Aetna Inc.
Subsequent Event [Line Items]
Number of shares one share of common stock is converted into | shares	0.8375
Cash received for each share converted	$ 125
Total transaction cost, including assumption of debt	$ 37,000,000,000