PARENT COMPANY STATEMENTS, Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Expenses [Abstract]
Interest on borrowings	$ 4,677	$ 3,904	$ 2,949
Acquisition expenses	(769)	25,986	1,706
Loss on debt prepayment	318	0	0
Other expenses	21,471	22,609	22,749
Income before tax benefit and equity in undistributed net income of subsidiaries	212,988	159,965	154,597
Income tax benefit	(44,347)	(9,248)	(50,785)
Net income	168,641	150,717	103,812
Other comprehensive (loss), net of tax [Abstract]
Changes in other comprehensive (loss)/income related to pension and other post retirement obligations	(11,204)	168	3,322
Changes in other comprehensive loss related to unrealized losses on available-for-sale securities	(30,402)	(11,065)	(14,714)
Other comprehensive (loss), net of tax	(41,398)	(10,897)	(11,392)
Comprehensive income	127,035	139,820	92,420
Parent Company [Member]
Dividends from subsidiaries [Abstract]
Bank subsidiary	98,000	91,000	89,000
Non-bank subsidiaries	9,250	35,500	1,750
Interest and dividends on investments	161	133	102
Total revenues	107,411	126,633	90,852
Expenses [Abstract]
Interest on borrowings	4,677	3,904	2,949
Acquisition expenses	0	91	429
Loss on debt prepayment	318	0	0
Other expenses	131	26	11
Total expenses	5,126	4,021	3,389
Income before tax benefit and equity in undistributed net income of subsidiaries	102,285	122,612	87,463
Income tax benefit	1,330	1,930	866
Income before equity in undistributed net income of subsidiaries	103,615	124,542	88,329
Equity in undistributed net income of subsidiaries	65,026	26,175	15,483
Net income	168,641	150,717	103,812
Other comprehensive (loss), net of tax [Abstract]
Changes in other comprehensive (loss)/income related to pension and other post retirement obligations	(11,204)	168	3,322
Changes in other comprehensive loss related to unrealized losses on available-for-sale securities	(30,402)	(11,065)	(14,714)
Other comprehensive (loss), net of tax	(41,606)	(10,897)	(11,392)
Comprehensive income	$ 127,035	$ 139,820	$ 92,420