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Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2020 USD ($) Customer shares | Dec. 31, 2019 USD ($) shares | Dec. 31, 2018 USD ($) shares | Dec. 30, 2017 USD ($) | Dec. 29, 2017 USD ($)
Significant Accounting Policies [Line Items] |  |  |  |  |
Contributions to ESOP | shares | 1,522,381 | 1,345,198 | 1,874,988 |  |
Repurchase of shares of common stock from ESOP | shares |  | 191,331 | 5,553,891 |  |
Redemption value of ESOP participants interest |  | $ 6,300 | $ 125,800 |  |
Adoption of ASC 606 | $ 1,861,417 | $ 1,660,756 | $ (921,076) |  | $ (1,049,916)
Concentration of Credit Risk |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Number of customers representing more than 10% of revenue | Customer | 0 |  |  |  |
Number of customers representing more than 10% of accounts receivable | Customer | 0 |  |  |  |
Revenue Benchmark | Concentration of Credit Risk |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Concentration risk percentage | 49.00% | 48.00% | 42.00% |  |
Accounts Receivable | Concentration of Credit Risk |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Concentration risk percentage | 19.00% | 18.00% |  |  |
Minimum |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Performance obligations payment terms from date of invoice | 30 days |  |  |  |
Intangible assets useful lives of underlying assets | 1 year |  |  |  |
Maximum |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Performance obligations payment terms from date of invoice | 120 days |  |  |  |
Intangible assets useful lives of underlying assets | 10 years |  |  |  |
Accumulated Deficit |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 | $ (120,569) | $ (218,025) | $ 12,445 |  | (186,035)
ASC 606 |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Change in accounting principle, adopted | true |  |  |  |
Change in accounting principle, adoption date | Dec. 30, 2017 |  |  |  |
Change In Accounting Principle Accounting Standards Update Transition Option Elected Extensible List | psn:AccountingStandardsUpdate201409ModifiedRetrospectiveMember |  |  |  |
ASC 606 | Revision of Prior Period, Accounting Standards Update, Adjustment |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 |  |  |  |  | (4,735)
ASC 606 | Accumulated Deficit |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 |  |  |  | $ 4,700 |
ASC 606 | Accumulated Deficit | Revision of Prior Period, Accounting Standards Update, Adjustment |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 |  |  |  |  | $ (4,735)
Accounting Standards Update 2018-09 |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Change in accounting principle, adopted | true |  |  |  |
Change In Accounting Principle Accounting Standards Update Transition Option Elected Extensible List | psn:AccountingStandardsUpdate201809ProspectiveMember |  |  |  |
Change in accounting principle, accounting standards update, immaterial effect | true |  |  |  |
ASU 2016-02 |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Change in accounting principle, adopted | true |  |  |  |
Change in accounting principle, adoption date | Jan. 01, 2019 |  |  |  |
Change In Accounting Principle Accounting Standards Update Transition Option Elected Extensible List | psn:AccountingStandardsUpdate201602ModifiedRetrospectiveMember |  |  |  |
Change in accounting principle, accounting standards update, immaterial effect | false |  |  |  |
ASU 2016-02 | Revision of Prior Period, Accounting Standards Update, Adjustment |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 |  |  | 52,608 |  |
ASU 2016-02 | Revision of Prior Period, Accounting Standards Update, Adjustment | Net Deferred Tax Asset |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 | $ 52,600 |  |  |  |
ASU 2016-02 | Revision of Prior Period, Accounting Standards Update, Adjustment | Deferred Tax Asset |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 | $ 700 |  |  |  |
ASU 2016-02 | Accumulated Deficit | Revision of Prior Period, Accounting Standards Update, Adjustment |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 |  |  | $ 52,608 |  |
ASC 2016-13 |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Change in accounting principle, adopted | true |  |  |  |
Change in accounting principle, adoption date | Dec. 15, 2019 |  |  |  |
Change in accounting principle, accounting standards update, immaterial effect | true |  |  |  |
ASC 2016-13 | Revision of Prior Period, Accounting Standards Update, Adjustment |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 |  | (1,000) |  |  |
ASC 2016-13 | Accumulated Deficit | Revision of Prior Period, Accounting Standards Update, Adjustment |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Adoption of ASC 606 |  | $ (1,000) |  |  |
Accounting Standards Update 2018-02 |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Change in accounting principle, adopted | true |  |  |  |
Change in accounting principle, adoption date | Jan. 01, 2019 |  |  |  |
Change in accounting principle, accounting standards update, immaterial effect | true |  |  |  |

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