Consolidated Statements of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Reclassification adjustments to cash flow hedges included in net income, tax	$ 1.3	$ 2.2	$ 2.2
Amortization of pension and postretirement plans actuarial loss and prior service cost, tax	4.0	4.9	4.2
Changes in unfunded employee benefit obligations, tax	$ (0.8)	$ 18.0	$ 15.7

Tax effect of the accumulated change in the value of either the projected benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption that has not been recognized in net periodic benefit cost. Also includes the tax effect of the cost (credit) resulting from a plan amendment that occurred during the period that has not been recognized in net periodic benefit cost.

No definition available.

Name:	pkg_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossAndNetPriorServiceCostsArisingDuringPeriodTax
Namespace Prefix:	pkg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration