Collaborations (Bayer HealthCare Pharmaceuticals Inc.) (Details) - Bayer [Member] - Nexavar [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) country	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of countries product is marketed and sold | country	100
Collaboration, royalty percentage in the high 30s	30.00%
Percentage of net profits after deducting certain partner related costs	50.00%
Other revenues [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration profit	$ 161	$ 167	$ 257
Royalty income	$ 133	$ 137	$ 72