Summary of Significant Accounting Policies - Comprehensive Earnings - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
COMPREHENSIVE EARNINGS
Tax rate used (as a percent)	21.00%		21.00%		21.00%	21.00%
Other comprehensive income (loss), tax (benefit)	$ 4,000		$ 14,200		$ (7,900)	$ 10,800
Changes in the balance of each component of accumulated other comprehensive earnings
Other comprehensive earnings (loss), net of tax	$ 15,177	$ (44,747)	$ 53,571	$ (13,031)	$ (29,570)	$ 40,540

Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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+ Details