Income Taxes - Schedule of Income Before Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Income Before Income Tax Domestic And Foreign Line Items
INCOME BEFORE INCOME TAX EXPENSE	$ 194,453	$ 253,832	$ 231,702
U.S.
Schedule Of Income Before Income Tax Domestic And Foreign Line Items
Income (loss) before income tax (benefit) expense	194,143	254,172	244,995
CANADA
Schedule Of Income Before Income Tax Domestic And Foreign Line Items
Income (loss) before income tax (benefit) expense	$ 310	$ (340)	$ (13,293)