PARENT COMPANY FINANCIAL INFORMATION - BALANCE SHEETS (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Cash and due from banks		$ 87,375	$ 79,171
Other assets		14,025	15,076
Total assets		6,123,494	6,498,097
Liabilities [Abstract]
Subordinated notes, net of unamortized debt issuance costs	[1]	98,407	98,248
Trust preferred subordinated debentures, net of unamortized debt issuance costs		60,246	60,241
Other liabilities		46,267	43,162
Total liabilities		5,392,203	5,743,957
Stockholders' Equity Attributable to Parent [Abstract]
Common stock: ($1.25 par value, 80,000,000 shares authorized and 37,845,224 shares issued at December 31, 2018 and 40,000,000 shares authorized and 37,802,352 shares issued at December 31, 2017)		47,307	47,253
Paid-in capital		762,470	757,439
Retained earnings		64,797	32,851
Treasury stock, at cost (4,120,475 at December 31, 2018 and 2,802,019 at December 31, 2017)		(93,055)	(47,105)
Accumulated other comprehensive loss		(50,228)	(36,298)
Total shareholders’ equity		731,291	754,140	$ 518,274	$ 444,062
Total liabilities and shareholders’ equity		6,123,494	6,498,097
Parent
ASSETS
Cash and due from banks		11,431	8,483
Other assets		4,290	10,350
Total assets		893,361	914,669
Liabilities [Abstract]
Subordinated notes, net of unamortized debt issuance costs		98,407	98,248
Trust preferred subordinated debentures, net of unamortized debt issuance costs		60,246	60,241
Other liabilities		3,417	2,040
Total liabilities		162,070	160,529
Stockholders' Equity Attributable to Parent [Abstract]
Common stock: ($1.25 par value, 80,000,000 shares authorized and 37,845,224 shares issued at December 31, 2018 and 40,000,000 shares authorized and 37,802,352 shares issued at December 31, 2017)		47,307	47,253
Paid-in capital		762,470	757,439
Retained earnings		64,797	32,851
Treasury stock, at cost (4,120,475 at December 31, 2018 and 2,802,019 at December 31, 2017)		(93,055)	(47,105)
Accumulated other comprehensive loss		(50,228)	(36,298)
Total shareholders’ equity		731,291	754,140
Total liabilities and shareholders’ equity		893,361	914,669
Parent | Bank subsidiaries
ASSETS
Investment in subsidiaries at equity in underlying net assets		875,814	894,010
Parent | Nonbank subsidiaries
ASSETS
Investment in subsidiaries at equity in underlying net assets		$ 1,826	$ 1,826

[1] This debt consists of subordinated notes with a remaining maturity greater than one year that qualify under the risk-based capital guidelines as Tier 2 capital, subject to certain limitations.