Employee Benefit Obligations - Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Pension Plans
Employee Benefit Obligations
Total assets.	$ 5,807.0	$ 1,304.0	$ 1,435.0
U.S.
Employee Benefit Obligations
Total assets	1,882.0	988.0
Other investments measured at net asset value	625.0	243.0
Total assets.	2,507.0	988.0	$ 1,098.0
U.S. | Cash and cash equivalents
Employee Benefit Obligations
Total assets.	185.0	69.0
U.S. | Consumer discretionary Securities
Employee Benefit Obligations
Total assets.	53.0	47.0
U.S. | Financials corporate equity securities
Employee Benefit Obligations
Total assets.	43.0	37.0
U.S. | Healthcare Corporate equity securities
Employee Benefit Obligations
Total assets.	27.0	26.0
U.S. | Industrials corporate equity securities
Employee Benefit Obligations
Total assets.	47.0	61.0
U.S. | Information technology corporate equity securities
Employee Benefit Obligations
Total assets.	66.0	53.0
U.S. | Other corporate equity securities
Employee Benefit Obligations
Total assets.	39.0	34.0
U.S. | FHLMC mortgage backed securities
Employee Benefit Obligations
Total assets.	17.0	14.0
U.S. | FNMA mortgage backed securities
Employee Benefit Obligations
Total assets.	64.0	56.0
U.S. | Municipal bonds
Employee Benefit Obligations
Total assets.	49.0
U.S. | Treasury bonds
Employee Benefit Obligations
Total assets.	85.0	32.0
U.S. | Other
Employee Benefit Obligations
Total assets.	26.0	24.0
U.S. | Corporate bonds and notes-Communications
Employee Benefit Obligations
Total assets.	58.0
U.S. | Corporate bonds and notes-Consumer discretionary
Employee Benefit Obligations
Total assets.	57.0
U.S. | Corporate bonds and notes-Consumer staples
Employee Benefit Obligations
Total assets.	64.0
U.S. | Corporate bonds and notes-Financials
Employee Benefit Obligations
Total assets.	280.0	92.0
U.S. | Corporate bonds and notes-Healthcare
Employee Benefit Obligations
Total assets.	98.0
U.S. | Corporate bonds and notes-Industrials
Employee Benefit Obligations
Total assets.	115.0	21.0
U.S. | Corporate bonds and notes-Information technology
Employee Benefit Obligations
Total assets.	84.0
U.S. | Corporate bonds and notes-Oil and gas
Employee Benefit Obligations
Total assets.	122.0	22.0
U.S. | Corporate bonds and notes-Private placement
Employee Benefit Obligations
Total assets.	76.0	37.0
U.S. | Corporate bonds and notes-Utilities
Employee Benefit Obligations
Total assets.	139.0
U.S. | Corporate bonds and notes-Other
Employee Benefit Obligations
Total assets.	71.0	103.0
U.S. | Commingled funds
Employee Benefit Obligations
Total assets.		745.0
U.S. | International Commingled Funds
Employee Benefit Obligations
Total assets.	17.0	16.0
U.S. | Other Commingled Funds
Employee Benefit Obligations
Total assets.		1.0
U.S. | Level 1
Employee Benefit Obligations
Total assets	385.0
U.S. | Level 1 | Cash and cash equivalents
Employee Benefit Obligations
Total assets.		3.0
U.S. | Level 1 | Consumer discretionary Securities
Employee Benefit Obligations
Total assets.	53.0	47.0
U.S. | Level 1 | Financials corporate equity securities
Employee Benefit Obligations
Total assets.	43.0	37.0
U.S. | Level 1 | Healthcare Corporate equity securities
Employee Benefit Obligations
Total assets.	27.0	26.0
U.S. | Level 1 | Industrials corporate equity securities
Employee Benefit Obligations
Total assets.	47.0	61.0
U.S. | Level 1 | Information technology corporate equity securities
Employee Benefit Obligations
Total assets.	66.0	53.0
U.S. | Level 1 | Other corporate equity securities
Employee Benefit Obligations
Total assets.	39.0	34.0
U.S. | Level 1 | Treasury bonds
Employee Benefit Obligations
Total assets.	85.0	32.0
U.S. | Level 1 | Other
Employee Benefit Obligations
Total assets.	8.0	12.0
U.S. | Level 1 | Commingled funds
Employee Benefit Obligations
Total assets.		321.0
U.S. | Level 1 | International Commingled Funds
Employee Benefit Obligations
Total assets.	17.0	16.0
U.S. | Level 2
Employee Benefit Obligations
Total assets	1,497.0
U.S. | Level 2 | Cash and cash equivalents
Employee Benefit Obligations
Total assets.	185.0	66.0
U.S. | Level 2 | FHLMC mortgage backed securities
Employee Benefit Obligations
Total assets.	17.0	14.0
U.S. | Level 2 | FNMA mortgage backed securities
Employee Benefit Obligations
Total assets.	64.0	56.0
U.S. | Level 2 | Municipal bonds
Employee Benefit Obligations
Total assets.	49.0
U.S. | Level 2 | Other
Employee Benefit Obligations
Total assets.	18.0	12.0
U.S. | Level 2 | Corporate bonds and notes-Communications
Employee Benefit Obligations
Total assets.	58.0
U.S. | Level 2 | Corporate bonds and notes-Consumer discretionary
Employee Benefit Obligations
Total assets.	57.0
U.S. | Level 2 | Corporate bonds and notes-Consumer staples
Employee Benefit Obligations
Total assets.	64.0
U.S. | Level 2 | Corporate bonds and notes-Financials
Employee Benefit Obligations
Total assets.	280.0	92.0
U.S. | Level 2 | Corporate bonds and notes-Healthcare
Employee Benefit Obligations
Total assets.	98.0
U.S. | Level 2 | Corporate bonds and notes-Industrials
Employee Benefit Obligations
Total assets.	115.0	21.0
U.S. | Level 2 | Corporate bonds and notes-Information technology
Employee Benefit Obligations
Total assets.	84.0
U.S. | Level 2 | Corporate bonds and notes-Oil and gas
Employee Benefit Obligations
Total assets.	122.0	22.0
U.S. | Level 2 | Corporate bonds and notes-Private placement
Employee Benefit Obligations
Total assets.	76.0	37.0
U.S. | Level 2 | Corporate bonds and notes-Utilities
Employee Benefit Obligations
Total assets.	139.0
U.S. | Level 2 | Corporate bonds and notes-Other
Employee Benefit Obligations
Total assets.	71.0	103.0
U.S. | Level 2 | Commingled funds
Employee Benefit Obligations
Total assets.		424.0
U.S. | Level 2 | Other Commingled Funds
Employee Benefit Obligations
Total assets.		1.0
Canada.
Employee Benefit Obligations
Total assets.		37.0
Canada. | Level 2 | Fixed income securities
Employee Benefit Obligations
Total assets.		7.0
Canada. | NAV
Employee Benefit Obligations
Other investments measured at net asset value	36.0
Canada. | NAV | Other Commingled Funds
Employee Benefit Obligations
Total assets.		30.0
United Kingdom. | Level 2
Employee Benefit Obligations
Total assets		272.0
Other investments measured at net asset value		261.0
Total assets.		11.0
United Kingdom. | Level 2 | Cash and cash equivalents
Employee Benefit Obligations
Total assets.		$ 11.0
Ireland | NAV
Employee Benefit Obligations
Other investments measured at net asset value	35.0
Rexam Plan Acquired | Level 1
Employee Benefit Obligations
Total assets	3,222.0
Other investments measured at net asset value	1,374.0
Total assets.	1,848.0
Rexam Plan Acquired | Level 1 | Cash and cash equivalents
Employee Benefit Obligations
Total assets.	279.0
Rexam Plan Acquired | Level 1 | Fixed income commingled funds
Employee Benefit Obligations
Total assets.	1,538.0
Rexam Plan Acquired | Level 1 | Other Commingled Funds
Employee Benefit Obligations
Total assets.	$ 31.0