PARENT COMPANY ONLY FINANCIAL INFORMATION (Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 39,809	$ 47,958	$ 30,131	$ 20,040	$ 37,851	$ 34,612	$ 45,169	$ 31,497	$ 137,938	$ 149,129	$ 116,998
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on extinguishment of debt									0	(375)	0
Other, net									(1,745)	(34,786)	(8,760)
NET CASH PROVIDED BY OPERATING ACTIVITIES									190,368	161,174	242,750
Cash flows from investing activities:
Repayment of advances from subsidiaries									0	6,000	0
Net assets acquired									641,315	76,071	212,197
NET CASH USED BY INVESTING ACTIVITIES									(2,301,426)	(573,970)	(124,220)
Cash flows from financing activities:
Proceeds on short-term revolving credit line									0	0	25,000
Proceeds from other borrowings									314,397	50	30,131
Repayments on short-term revolving credit line									0	0	(25,000)
Repayments of other borrowings									(134,244)	(20,693)	(59,157)
Payment for the redemption of debt									0	(2,125)	0
Cash dividends paid									(31,906)	(24,607)	(19,357)
Purchase of treasury stock									0	0	(97)
Proceeds from issuance of preferred stock									110,705	0	0
Proceeds from issuance of common stock									3,004	661	489
NET CASH PROVIDED (USED) BY FINANCING ACTIVITIES									2,070,227	517,900	(40,903)
Net increase (decrease) in cash and cash equivalents									(40,831)	105,104	77,627
Cash and cash equivalents at beginning of year				378,734				273,630	378,734	273,630	196,003
CASH AND CASH EQUIVALENTS AT END OF PERIOD	337,903				378,734				337,903	378,734	273,630
Supplemental disclosure:
Dividends declared, not paid	2,013				0				2,013	0	0
Conversion/redemption of Series D preferred stock to common stock									0	0	938
Stock consideration granted for acquisitions									217,202	92,258	238,075
Parent
Cash flows from operating activities:
Net income									137,938	149,129	116,998
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed earnings of subsidiaries									(73,430)	(34,307)	(52,570)
Gain on extinguishment of debt									0	(375)	0
Increase in accrued expenses and other liabilities									8,419	3,274	5,336
Increase in other assets									(19,168)	(12,248)	(1,559)
Excess tax (expense) benefit from stock based compensation									(93)	270	674
Other, net									6,375	4,103	5,401
NET CASH PROVIDED BY OPERATING ACTIVITIES									60,041	109,846	74,280
Cash flows from investing activities:
Capital contributions to subsidiaries									(70,000)	(46,583)	(30,696)
Net assets acquired									(41,982)	(594)	(13,504)
NET CASH USED BY INVESTING ACTIVITIES									(111,982)	(41,177)	(44,200)
Cash flows from financing activities:
Proceeds on short-term revolving credit line									0	0	25,000
Proceeds from other borrowings									0	0	30,000
Repayments on short-term revolving credit line									0	0	(25,000)
Repayments of other borrowings									(7,000)	(20,023)	(25,759)
Payment for the redemption of debt									0	(2,500)	0
Cash dividends paid									(31,906)	(24,607)	(19,357)
Purchase of treasury stock									0	0	(97)
Proceeds from issuance of preferred stock									110,705	0	0
Proceeds from issuance of common stock									3,004	661	489
NET CASH PROVIDED (USED) BY FINANCING ACTIVITIES									74,803	(46,469)	(14,724)
Net increase (decrease) in cash and cash equivalents									22,862	22,200	15,356
Cash and cash equivalents at beginning of year				$ 61,866				$ 39,666	61,866	39,666	24,310
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 84,728				$ 61,866				84,728	61,866	39,666
Supplemental disclosure:
Conversion of convertible debt to common stock									14,891	0	0
Conversion/redemption of Series D preferred stock to common stock									0	0	938
Stock consideration granted for acquisitions									$ 217,202	$ 92,258	$ 238,075