Interim Consolidated Financial Statements - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Summary Of Significant Accounting Policy [Line Items]
Decrease in retained earnings	$ 125,554		$ 118,147
Topic 326 [Member]
Summary Of Significant Accounting Policy [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
ASU No. 2017-04 [Member]
Summary Of Significant Accounting Policy [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect	true
ASU No. 2018-13 [Member]
Summary Of Significant Accounting Policy [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect	true
ASU No. 2018-15 [Member]
Summary Of Significant Accounting Policy [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect	true
Cumulative Effect Adjustment [Member] | Topic 326 [Member]
Summary Of Significant Accounting Policy [Line Items]
Decrease in retained earnings		$ (200)