New Accounting Pronouncements - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2020		Dec. 31, 2019		Jun. 30, 2019	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	$ 200,300	[1]	$ 101,788	[1]	$ 102,092	$ 103,661		$ 103,635
Reduction to retained earnings, net of deferred tax balances	(1,692,289)		$ (1,672,438)
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset							$ 58,200
Lease liability							$ 63,000
ASU Nos. 2016-13 [Member] | Cumulative Effect Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	9,000
Reduction to retained earnings, net of deferred tax balances	$ 7,000

[1] As of December 31, 2019, this line represents the Allowance for loan losses. See further discussion of this change in Note 3, “New Accounting Pronouncements.”