Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 21, 2020	Jun. 30, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Trading Symbol	PKG
Entity Registrant Name	PACKAGING CORP OF AMERICA
Security Exchange Name	NYSE
Title of 12(b) Security	Common Stock, par value $0.01 per share
Entity Interactive Data Current	Yes
Entity File Number	1-15399
Entity Tax Identification Number	36-4277050
Entity Address, Address Line One	1 North Field Court
Entity Address, City or Town	Lake Forest
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60045
City Area Code	847
Local Phone Number	482-3000
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Document Transition Report	false
Entity Central Index Key	0000075677
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		94,652,815
Entity Public Float			$ 8,891,651,488
Documents Incorporated by Reference	Specified portions of the Proxy Statement for the Registrant's 2020 Annual Meeting of Stockholders are incorporated by reference to the extent indicated in Part III of this Form 10-K.