Investment Securities Held-to-Maturity - Company's Securities Held-to-Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Within one year, Amortized Cost	$ 90,437
After one but within five years, Amortized Cost	1,921,419
After five but within ten years, Amortized Cost	280,016
More than ten years, Amortized Cost	12,202
Amortized Cost	2,304,074	$ 2,351,120
Within one year, Fair Value	91,896
After one but within five years, Fair Value	1,971,224
After five but within ten years, Fair Value	289,074
More than ten years, Fair Value	12,833
Estimated Fair Value	$ 2,365,027	$ 2,361,304

Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing in next fiscal year through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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-Publisher FASB
-Name Accounting Standards Codification
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