Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Income Statement [Abstract]
Net sales		$ 7,014.6	$ 6,444.9	[1]	$ 5,779.0	[1]
Cost of sales		(5,369.3)	(4,974.1)		(4,502.9)
Gross profit		1,645.3	1,470.8	[2]	1,276.1
Selling and administrative expenses		(536.4)	(519.9)		(468.5)
Other expense, net		(41.2)	(18.4)		(24.3)
Income from operations	[3]	1,067.7	932.5	[2]	783.3
Interest expense, net and other	[3]	(97.2)	(103.9)	[4]	(94.8)
Income before taxes	[3]	970.5	828.6		688.5
(Provision) benefit for income taxes		(232.5)	(160.0)		(238.9)
Net income		$ 738.0	$ 668.6		$ 449.6
Net income per common share:
Basic		$ 7.82	$ 7.09		$ 4.76
Diluted		7.80	7.07		4.75
Dividends declared per common share		$ 3.00	$ 2.52		$ 2.36
Statements of Comprehensive Income:
Net income		$ 738.0	$ 668.6		$ 449.6
Foreign currency translation adjustment		(0.1)	(0.2)
Reclassification adjustments to cash flow hedges included in net income, net of tax of $1.3 million, $2.2 million, and $2.2 million for 2018, 2017, and 2016, respectively		4.0	3.5		3.5
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $4.0 million, $4.9 million, and $4.2 million for 2018, 2017, and 2016, respectively		11.8	8.2		6.7
Changes in unfunded employee benefit obligations, net of tax of ($0.8) million, $18.0 million, and $15.7 million for 2018, 2017, and 2016, respectively		2.4	(28.8)		(24.9)
Other comprehensive income (loss)		18.1	(17.3)		(14.7)
Comprehensive income		$ 756.1	$ 651.3		$ 434.9

[1] Prior periods have not been adjusted under the modified retrospective method for Topic 606.

[2] (a)Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost and applied this standard retrospectively to the prior period reflected herein. This new standard requires the presentation of non-service cost components of net periodic benefits expense to be shown separately outside the subtotal of operating income in the income statement. See Note 2, Summary of Significant Accounting Policies, for more information. The components of our financial statements affected by the change in presentation of operating and non-operating pension expense as originally reported in 2017 and as adjusted for the requirements per the new standard are as follows (dollars in millions): First quarter, 2017 As Reported Non-Operating Pension Adjustment Adjusted Gross profit $338.5 $(0.3) $338.2 Income from operations 203.1 0.3 203.4 Second quarter, 2017 Gross profit $364.6 $(0.3) $364.3 Income from operations 233.8 0.3 234.1 Third quarter, 2017 Gross profit $397.3 $(0.3) $397.0 Income from operations 242.3 0.3 242.6 Fourth quarter, 2017 Gross profit $371.7 $(0.3) $371.4 Income from operations 252.0 0.3 252.3 Full year 2017 Gross profit $1,472.2 $(1.4) $1,470.8 Income from operations 931.2 1.3 932.5

[3] (a)Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost and applied this standard retrospectively to the prior period reflected herein. This new standard requires the presentation of non-service cost components of net periodic benefits expense to be shown separately outside the subtotal of operating income in the income statement. See Note 2, Summary of Significant Accounting Policies, for more information. The components of our financial statements affected by the change in presentation of operating and non-operating pension expense as originally reported in 2017 and 2016 and as adjusted for the requirements per the new standard are as follows (dollars in millions): Segment income (loss) Year Ended December 31, 2017 As Reported Non-Operating Pension Adjustment Year Ended December 31, 2017 Adjusted Packaging $943.7 $6.6 $950.3 Paper 61.5 (7.5) 54.0 Corporate (74.0) 2.2 (71.8) Income from operations 931.2 1.3 932.5 Interest expense, net and other (102.6) (1.3) (103.9) Income before taxes $828.6 $— $828.6 Segment income (loss) Year Ended December 31, 2016 As Reported Non-Operating Pension Adjustment Year Ended December 31, 2016 Adjusted Packaging $711.1 $7.4 $718.5 Paper 138.1 (6.4) 131.7 Corporate (68.9) 2.0 (66.9) Income from operations 780.3 3.0 783.3 Interest expense, net and other (91.8) (3.0) (94.8) Income before taxes $688.5 $— $688.5

[4] Includes $1.8 million of expense related to the write-off of deferred debt issuance costs in connection with the December 2017 debt refinancing.