Goodwill and Other Intangibles - Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 180,867	$ 180,867	$ 180,867
Commercial Banking [Member]
Goodwill And Other Intangible Assets [Line Items]
Goodwill	59,419	59,419	59,419
Institutional Banking [Member]
Goodwill And Other Intangible Assets [Line Items]
Goodwill	51,332	51,332	51,332
Personal Banking [Member]
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 70,116	$ 70,116	$ 70,116