XML 44 R37.htm IDEA: XBRL DOCUMENT
v3.25.1

Cash, Cash Equivalents, and Marketable Debt Securities (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2025
Cash, Cash Equivalents, and Short-Term Investments [Abstract] |
Schedule of Cash and Available-For-Sale Debt Securities by Major Asset Category | The following table shows the Company’s cash, cash equivalents, and available-for-sale ("AFS") debt securities by major asset category at March 31, 2025 and December 31, 2024 (in millions):
|  | March 31, 2025 |
|  | Adjusted Cost Basis |  |  | Unrealized Gain |  |  | Unrealized Loss |  |  | Fair Value |  |  | Cash and Cash Equivalents |  |  | Short-Term Marketable Debt Securities |  |  | Long-Term Marketable Debt Securities |
Cash and cash equivalents |  | $ | 745.0 |  |  | $ | — |  |  | $ | — |  |  | $ | 745.0 |  |  | $ | 745.0 |  |  | $ | — |  |  | $ | — |
Level 1 (a): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury securities |  |  | 32.1 |  |  |  | — |  |  |  | — |  |  |  | 32.1 |  |  |  | — |  |  |  | 20.0 |  |  |  | 12.1 |
Money market funds |  |  | 5.2 |  |  |  | — |  |  |  | — |  |  |  | 5.2 |  |  |  | 5.2 |  |  |  | — |  |  |  | — |
Subtotal |  |  | 37.3 |  |  |  | — |  |  |  | — |  |  |  | 37.3 |  |  |  | 5.2 |  |  |  | 20.0 |  |  |  | 12.1 |
Level 2 (b): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate debt securities |  |  | 128.2 |  |  |  | 0.4 |  |  |  | — |  |  |  | 128.6 |  |  |  | 1.5 |  |  |  | 70.6 |  |  |  | 56.5 |
U.S. government agency securities |  |  | 2.7 |  |  |  | — |  |  |  | — |  |  |  | 2.7 |  |  |  | — |  |  |  | — |  |  |  | 2.7 |
Certificates of deposit |  |  | 0.8 |  |  |  | — |  |  |  | — |  |  |  | 0.8 |  |  |  | — |  |  |  | 0.8 |  |  |  | — |
Subtotal |  |  | 131.7 |  |  |  | 0.4 |  |  |  | — |  |  |  | 132.1 |  |  |  | 1.5 |  |  |  | 71.4 |  |  |  | 59.2 |
Total |  | $ | 914.0 |  |  | $ | 0.4 |  |  | $ | — |  |  | $ | 914.4 |  |  | $ | 751.7 |  |  | $ | 91.4 |  |  | $ | 71.3 |
|  | December 31, 2024 |
|  | Adjusted Cost Basis |  |  | Unrealized Gain |  |  | Unrealized Loss |  |  | Fair Value |  |  | Cash and Cash Equivalents |  |  | Short-Term Marketable Debt Securities |  |  | Long-Term Marketable Debt Securities |
Cash and cash equivalents |  | $ | 684.8 |  |  | $ | — |  |  | $ | — |  |  | $ | 684.8 |  |  | $ | 684.8 |  |  | $ | — |  |  | $ | — |
Level 1 (a): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury securities |  |  | 30.8 |  |  |  | 0.1 |  |  |  | — |  |  |  | 30.9 |  |  |  | — |  |  |  | 23.0 |  |  |  | 7.9 |
Money market funds |  |  | 0.2 |  |  |  | — |  |  |  | — |  |  |  | 0.2 |  |  |  | 0.2 |  |  |  | — |  |  |  | — |
Subtotal |  |  | 31.0 |  |  |  | 0.1 |  |  |  | — |  |  |  | 31.1 |  |  |  | 0.2 |  |  |  | 23.0 |  |  |  | 7.9 |
Level 2 (b): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate debt securities |  |  | 131.2 |  |  |  | 0.3 |  |  |  | — |  |  |  | 131.5 |  |  |  | — |  |  |  | 75.8 |  |  |  | 55.7 |
Certificates of deposit |  |  | 2.4 |  |  |  | — |  |  |  | — |  |  |  | 2.4 |  |  |  | — |  |  |  | 2.4 |  |  |  | — |
U.S. government agency securities |  |  | 2.4 |  |  |  | — |  |  |  | — |  |  |  | 2.4 |  |  |  | — |  |  |  | 0.8 |  |  |  | 1.6 |
Subtotal |  |  | 136.0 |  |  |  | 0.3 |  |  |  | — |  |  |  | 136.3 |  |  |  | — |  |  |  | 79.0 |  |  |  | 57.3 |
Total |  | $ | 851.8 |  |  | $ | 0.4 |  |  | $ | — |  |  | $ | 852.2 |  |  | $ | 685.0 |  |  | $ | 102.0 |  |  | $ | 65.2 |
(a) Valuations based on quoted prices for identical assets or liabilities in active markets. (b) Valuations based on observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data.
Schedule of Marketable Debt Securities in Continuous Loss Position | The following tables provide information about the Company’s marketable debt securities that have been in a continuous loss position as of March 31, 2025 and December 31, 2024 (in millions, except number of marketable debt securities in a loss position):
|  | March 31, 2025 |
|  | Fair Value of Marketable Debt Securities in a Loss Position < 12 Months |  |  | Number of Marketable Debt Securities in a Loss Position < 12 Months |  |  | Unrealized Losses < 12 Months (c) |  |  | Fair Value of Marketable Debt Securities in a Loss Position ≥ 12 Months |  |  | Number of Marketable Debt Securities in a Loss Position ≥ 12 Months |  |  | Unrealized Losses ≥ 12 Months (c) |
Corporate debt securities |  | $ | 16.7 |  |  |  | 23 |  |  | $ | — |  |  | $ | — |  |  |  | — |  |  | $ | — |
U.S. government agency securities |  |  | 0.8 |  |  |  | 1 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |
U.S. Treasury securities |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 1.2 |  |  |  | 1 |  |  |  | — |
|  | $ | 17.5 |  |  |  | 24 |  |  | $ | — |  |  | $ | 1.2 |  |  |  | 1 |  |  | $ | — |
|  | December 31, 2024 |
|  | Fair Value of Marketable Debt Securities in a Loss Position < 12 Months |  |  | Number of Marketable Debt Securities in a Loss Position < 12 Months |  |  | Unrealized Losses < 12 Months |  |  | Fair Value of Marketable Debt Securities in a Loss Position ≥ 12 Months |  |  | Number of Marketable Debt Securities in a Loss Position ≥ 12 Months |  |  | Unrealized Losses ≥ 12 Months (c) |
Corporate debt securities |  | $ | 16.5 |  |  |  | 26 |  |  | $ | 0.1 |  |  | $ | 2.7 |  |  |  | 4 |  |  | $ | — |
U.S. Treasury securities |  |  | 3.1 |  |  |  | 4 |  |  |  | — |  |  |  | 6.7 |  |  |  | 5 |  |  |  | — |
U.S. government agency securities |  |  | 0.8 |  |  |  | 1 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |
|  | $ | 20.4 |  |  |  | 31 |  |  | $ | 0.1 |  |  | $ | 9.4 |  |  |  | 9 |  |  | $ | — |
(c) Unrealized losses were insignificant for the period presented.

X
- Definition Schedule of Marketable Debt Securities in Continuous Loss Position [Table Text Block] + References No definition available. + Details
Name: | pkg_ScheduleOfMarketableDebtSecuritiesInContinuousLossPositionTableTextBlock
Namespace Prefix: | pkg_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_CashCashEquivalentsAndShortTermInvestmentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the reconciliation of available-for-sale securities from cost basis to fair value. + References No definition available. + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration