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Employee Benefit Plans and Other Postretirement Plans - Fair Value Measurements of Plan Assets (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Company contributions |  | $ 57,100,000 | $ 57,100,000 | $ 400,000 |
Fair value of plan assets |  | 764,400,000 | 764,400,000 |  | $ 830,400,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period |  | 764,400,000 |  |  |
Fair value of plan assets at plan year end |  | 830,400,000 | 764,400,000 |  |
Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets |  | 6,400,000 | 6,400,000 |  | 5,700,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period |  | 6,400,000 |  |  |
Sales |  | (700,000) |  |  |
Fair value of plan assets at plan year end |  | 5,700,000 | 6,400,000 |  |
Short-term Investments |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 4,100,000 | 4,100,000 |  | 1,500,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 4,100,000 |  |  |
Fair value of plan assets at plan year end | [1] | 1,500,000 | 4,100,000 |  |
Short-term Investments | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 0 |  |  |
Fair value of plan assets at plan year end | [1] | 0 | 0 |  |
Short-term Investments | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 4,100,000 | 4,100,000 |  | 1,500,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 4,100,000 |  |  |
Fair value of plan assets at plan year end | [1] | 1,500,000 | 4,100,000 |  |
Short-term Investments | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 0 |  |  |
Fair value of plan assets at plan year end | [1] | 0 | 0 |  |
Domestic equities (Mutual Funds) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 47,100,000 | 47,100,000 |  | 65,700,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 47,100,000 |  |  |
Fair value of plan assets at plan year end | [2] | 65,700,000 | 47,100,000 |  |
Domestic equities (Mutual Funds) | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 47,100,000 | 47,100,000 |  | 65,700,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 47,100,000 |  |  |
Fair value of plan assets at plan year end | [2] | 65,700,000 | 47,100,000 |  |
Domestic equities (Mutual Funds) | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 0 |  |  |
Fair value of plan assets at plan year end | [2] | 0 | 0 |  |
Domestic equities (Mutual Funds) | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 0 |  |  |
Fair value of plan assets at plan year end | [2] | 0 | 0 |  |
International equities (Mutual Funds) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 50,700,000 | 50,700,000 |  | 68,700,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 50,700,000 |  |  |
Fair value of plan assets at plan year end | [2] | 68,700,000 | 50,700,000 |  |
International equities (Mutual Funds) | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 50,700,000 | 50,700,000 |  | 68,700,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 50,700,000 |  |  |
Fair value of plan assets at plan year end | [2] | 68,700,000 | 50,700,000 |  |
International equities (Mutual Funds) | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 0 |  |  |
Fair value of plan assets at plan year end | [2] | 0 | 0 |  |
International equities (Mutual Funds) | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 0 |  |  |
Fair value of plan assets at plan year end | [2] | 0 | 0 |  |
Real Estate |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 8,500,000 | 8,500,000 |  | 9,600,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 8,500,000 |  |  |
Fair value of plan assets at plan year end | [2] | 9,600,000 | 8,500,000 |  |
Real Estate | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 8,500,000 | 8,500,000 |  | 9,600,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 8,500,000 |  |  |
Fair value of plan assets at plan year end | [2] | 9,600,000 | 8,500,000 |  |
Real Estate | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 0 |  |  |
Fair value of plan assets at plan year end | [2] | 0 | 0 |  |
Real Estate | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 0 |  |  |
Fair value of plan assets at plan year end | [2] | 0 | 0 |  |
Fixed Income (Mutual Funds) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 156,500,000 | 156,500,000 |  | 173,200,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 156,500,000 |  |  |
Fair value of plan assets at plan year end | [2] | 173,200,000 | 156,500,000 |  |
Fixed Income (Mutual Funds) | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 156,500,000 | 156,500,000 |  | 108,400,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 156,500,000 |  |  |
Fair value of plan assets at plan year end | [2] | 108,400,000 | 156,500,000 |  |
Fixed Income (Mutual Funds) | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 0 | 0 |  | 64,800,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 0 |  |  |
Fair value of plan assets at plan year end | [2] | 64,800,000 | 0 |  |
Fixed Income (Mutual Funds) | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [2] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [2] | 0 |  |  |
Fair value of plan assets at plan year end | [2] | 0 | 0 |  |
Domestic equities (Common/collective trusts) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 104,400,000 | 104,400,000 |  | 107,900,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 104,400,000 |  |  |
Fair value of plan assets at plan year end | [1] | 107,900,000 | 104,400,000 |  |
Domestic equities (Common/collective trusts) | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 0 |  |  |
Fair value of plan assets at plan year end | [1] | 0 | 0 |  |
Domestic equities (Common/collective trusts) | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 104,400,000 | 104,400,000 |  | 107,900,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 104,400,000 |  |  |
Fair value of plan assets at plan year end | [1] | 107,900,000 | 104,400,000 |  |
Domestic equities (Common/collective trusts) | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 0 |  |  |
Fair value of plan assets at plan year end | [1] | 0 | 0 |  |
International equities (Common/Collective Trust Funds) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 121,600,000 | 121,600,000 |  | 124,500,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 121,600,000 |  |  |
Fair value of plan assets at plan year end | [1] | 124,500,000 | 121,600,000 |  |
International equities (Common/Collective Trust Funds) | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 0 |  |  |
Fair value of plan assets at plan year end | [1] | 0 | 0 |  |
International equities (Common/Collective Trust Funds) | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 121,600,000 | 121,600,000 |  | 124,500,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 121,600,000 |  |  |
Fair value of plan assets at plan year end | [1] | 124,500,000 | 121,600,000 |  |
International equities (Common/Collective Trust Funds) | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 0 |  |  |
Fair value of plan assets at plan year end | [1] | 0 | 0 |  |
Fixed Income (Common/Collective Trust Funds) [Member] |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 263,000,000 | 263,000,000 |  | 271,600,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 263,000,000 |  |  |
Fair value of plan assets at plan year end | [1] | 271,600,000 | 263,000,000 |  |
Fixed Income (Common/Collective Trust Funds) [Member] | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 0 |  |  |
Fair value of plan assets at plan year end | [1] | 0 | 0 |  |
Fixed Income (Common/Collective Trust Funds) [Member] | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 263,000,000 | 263,000,000 |  | 271,600,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 263,000,000 |  |  |
Fair value of plan assets at plan year end | [1] | 271,600,000 | 263,000,000 |  |
Fixed Income (Common/Collective Trust Funds) [Member] | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [1] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [1] | 0 |  |  |
Fair value of plan assets at plan year end | [1] | 0 | 0 |  |
Private Equity Securities |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [3] | 6,400,000 | 6,400,000 |  | 5,700,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [3] | 6,400,000 |  |  |
Fair value of plan assets at plan year end | [3] | 5,700,000 | 6,400,000 |  |
Private Equity Securities | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [3] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [3] | 0 |  |  |
Fair value of plan assets at plan year end | [3] | 0 | 0 |  |
Private Equity Securities | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [3] | 0 | 0 |  | 0
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [3] | 0 |  |  |
Fair value of plan assets at plan year end | [3] | 0 | 0 |  |
Private Equity Securities | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets | [3] | 6,400,000 | 6,400,000 |  | 5,700,000
Investment commitment |  |  |  |  | 15,000,000
Unfunded portion of investment commitment |  |  |  |  | 5,000,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period | [3] | 6,400,000 |  |  |
Fair value of plan assets at plan year end | [3] | 5,700,000 | 6,400,000 |  |
Total Securities at Fair Value |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets |  | 762,300,000 | 762,300,000 |  | 828,400,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period |  | 762,300,000 |  |  |
Fair value of plan assets at plan year end |  | 828,400,000 | 762,300,000 |  |
Total Securities at Fair Value | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets |  | 262,800,000 | 262,800,000 |  | 252,400,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period |  | 262,800,000 |  |  |
Fair value of plan assets at plan year end |  | 252,400,000 | 262,800,000 |  |
Total Securities at Fair Value | Significant other observable inputs (Level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets |  | 493,100,000 | 493,100,000 |  | 570,300,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period |  | 493,100,000 |  |  |
Fair value of plan assets at plan year end |  | 570,300,000 | 493,100,000 |  |
Total Securities at Fair Value | Significant unobservable input (Level 3) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets |  | 6,400,000 | 6,400,000 |  | 5,700,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period |  | 6,400,000 |  |  |
Fair value of plan assets at plan year end |  | 5,700,000 | 6,400,000 |  |
Receivables and Accruals, Net [Member] |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value of plan assets |  | 2,100,000 | 2,100,000 |  | $ 2,000,000
Level 3 fair value of pension plans' assets [Roll Forward] |  |  |  |  |
Plan assets at fair value at beginning of period |  | 2,100,000 |  |  |
Fair value of plan assets at plan year end |  | $ 2,000,000 | $ 2,100,000 |  |
[1] | Investments in common/collective trust funds valued using net asset values (NAV) provided by the administrator of the funds. The NAV is based on the value of the underlying assets owned by the fund, minus its liabilities, and then divided by the number of units outstanding. While the underlying assets are actively traded on an exchange, the funds are not. There are currently no redemption restrictions on these investments. There are certain funds with one-day redeemable notice.
[2] | Investments in mutual funds valued at quoted market values on the last business day of the fiscal year.
[3] | Investments in this category are invested in the Pantheon Global Secondary Fund IV, LP. The fund specializes in investments in the private equity secondary market and occasionally directly in private companies to maximize capital growth. Fund investments are carried at fair value as determined quarterly using the market approach to estimate the fair value of private investments. The market approach utilizes prices and other relevant information generated by market transactions, type of security, size of the position, degree of liquidity, restrictions on the disposition, latest round of financing data, current financial position, and operating results, among other factors. In circumstances where fair values are not provided with respect to any of the company's fund investments, the investment advisor will seek to determine the fair value of such investments based on information provided by the general partners or managers of such funds or from other sources. Audited financial statements are provided by fund management annually. Notwithstanding the above, the variety of valuation bases adopted and quality of management data of the ultimate underlying investee companies means that there are inherent difficulties in determining the value of the investments. Amounts realized on the sale of these investments may differ from the calculated values. Boise had originally committed to a $15.0 million investment, with $5.0 million of the commitment unfunded at December 31, 2016.

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- Definition Sales of plan assets that occured during the period. + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Commitment to invest in private equity securities. + References No definition available. + Details
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Namespace Prefix: | pkg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Unfunded portion of commitment to invest in private equity securities. + References No definition available. + Details
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Namespace Prefix: | pkg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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