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Interim Consolidated Financial Statements - Additional Information (Detail) - USD ($) | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020 | Jan. 01, 2020
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Total revenues | $ 118,136,000 | $ 108,577,000 | $ 360,587,000 | $ 328,463,000 |  |
Decrease in retained earnings | $ 144,802,000 |  | $ 144,802,000 |  | $ 127,981,000 |
ASU No. 2016-13 [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted | true |  | true |  |  |
Change in accounting principle, accounting standards update, adoption date | Jan. 01, 2020 |  | Jan. 01, 2020 |  |  |
ASU No. 2019-12 [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted | true |  | true |  |  |
Change in accounting principle, accounting standards update, adoption date | Jan. 01, 2021 |  | Jan. 01, 2021 |  |  |
Change in accounting principle, accounting standards update, immaterial effect | true |  | true |  |  |
ASU No. 2017-04 [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted | true |  | true |  |  |
Change in accounting principle, accounting standards update, adoption date | Jan. 01, 2020 |  | Jan. 01, 2020 |  |  |
Change in accounting principle, accounting standards update, immaterial effect | true |  | true |  |  |
ASU No. 2018-13 [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted | true |  | true |  |  |
Change in accounting principle, accounting standards update, adoption date | Jan. 01, 2020 |  | Jan. 01, 2020 |  |  |
Change in accounting principle, accounting standards update, immaterial effect | true |  | true |  |  |
ASU No. 2018-15 [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted | true |  | true |  |  |
Change in accounting principle, accounting standards update, adoption date | Jan. 01, 2020 |  | Jan. 01, 2020 |  |  |
Change in accounting principle, accounting standards update, immaterial effect | true |  | true |  |  |
Cumulative Effect, Period of Adoption, Adjustment [Member] | ASU No. 2016-13 [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Decrease in retained earnings |  |  |  |  |  | $ 200,000
Consulting [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Total revenues | $ 37,393,000 | 33,001,000 | $ 116,903,000 | 98,464,000 |  |
Research [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Total revenues | $ 79,876,000 | 74,445,000 | 235,846,000 | 223,746,000 |  |
Reclassification Adjustment [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Total revenues |  |  | $ 0 |  |  |
Reclassification Adjustment [Member] | Consulting [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Total revenues |  |  |  | $ 4,500,000 |  |
Reclassification Adjustment [Member] | Research [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |  |  |  |
Total revenues |  | $ 1,600,000 |  |  |  |

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