Derivative Financial Instruments - Information about Hedged Items Included in Consolidated Balance Sheet (Detail) - Long-term Debt [Member] - Derivatives Designated and Qualifying as Hedging Instruments [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 1,750,048	$ 3,840,775
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 101,326		$ 43,640