Intangible Assets - Reconciliation of Goodwill (Detail) - USD ($) $ in Thousands		6 Months Ended
	Dec. 03, 2021	Jun. 30, 2022
Goodwill [Line Items]
Goodwill at December 31, 2021		$ 1,886,494
Goodwill at March 31, 2022		1,888,889
Community Bankers Trust Corporation [Member]
Goodwill [Line Items]
Addition to goodwill from Community Bankers Trust acquisition	$ 78,849	2,395
Goodwill at March 31, 2022	$ 78,849
Community Banking [Member]
Goodwill [Line Items]
Goodwill at December 31, 2021		1,881,179
Goodwill at March 31, 2022		1,883,574
Community Banking [Member] | Community Bankers Trust Corporation [Member]
Goodwill [Line Items]
Addition to goodwill from Community Bankers Trust acquisition		2,395
Mortgage Banking [Member]
Goodwill [Line Items]
Goodwill at December 31, 2021		5,315
Goodwill at March 31, 2022		5,315
Mortgage Banking [Member] | Community Bankers Trust Corporation [Member]
Goodwill [Line Items]
Addition to goodwill from Community Bankers Trust acquisition		$ 0