Summary of Significant Accounting Policies - Company Held Significant Investment (Detail)	Dec. 31, 2017
RTS Packaging JVCO
Noncontrolling Interest [Line Items]
Ownership interest percentage	35.00%
Cascades Conversion, Inc.
Noncontrolling Interest [Line Items]
Ownership interest percentage	50.00%
Cascades Sonoco, Inc.
Noncontrolling Interest [Line Items]
Ownership interest percentage	50.00%
Showa Products Company Ltd.
Noncontrolling Interest [Line Items]
Ownership interest percentage	20.00%
Conitex Sonoco Holding BVI Ltd.
Noncontrolling Interest [Line Items]
Ownership interest percentage	30.00%
Weidenhammer New Packaging, LLC
Noncontrolling Interest [Line Items]
Ownership interest percentage	40.00%