Business Combinations - Schedule of Supplemental Pro Forma Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	8 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings per share, Pro forma:
Net interest income, Pro forma			$ 194,365	$ 199,415
Provision for loan losses, Pro forma			1,281	2,564
Non-interest income, Pro forma			31,046	28,432
Non-interest expense, Pro forma			143,338	172,621
Provision (benefit) for income taxes, Pro forma			15,620	10,423
Net income, Pro forma			$ 65,172	$ 42,239
Fully diluted, Pro forma (in usd per share)			$ 1.27	$ 0.83
Capital Bank
Earnings per share, Actual:
Net interest income, Actual	$ 12,700
Provision for loan losses, Actual	280
Non-interest income, Actual	991
Non-interest expense, Actual	11,035
Provision (benefit) for income taxes, Actual	499
Net income, Actual	$ 1,877
Sun Bancorp, Inc.
Earnings per share, Actual:
Net interest income, Actual		$ 47,619
Provision for loan losses, Actual		884
Non-interest income, Actual		5,654
Non-interest expense, Actual		26,150
Provision (benefit) for income taxes, Actual		5,510
Net income, Actual		$ 20,729