Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Valley Commerce Bancorp [Member]	Community Bank [Member]	Common Stock [Member]	Common Stock [Member] Valley Commerce Bancorp [Member]	Common Stock [Member] Community Bank [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2016	$ 990,862			$ 531,192			$ 449,499	$ 10,171
Beginning balance, shares at Dec. 31, 2016				108,252
Cumulative adjustment upon adoption of ASU 2016-09	50			$ 116			(66)
Repurchase of common stock	(997)			$ (997)
Repurchase of common stock, shares				(45)
Issuance of common stock for acquisition		$ 37,637			$ 37,637
Issuance of common stock for acquisition, shares					1,634
Exercise of stock options	2,537			$ 2,537
Exercise of stock options, shares				270
Shares issued pursuant to stock-based compensation plan	2,200			$ 2,200
Shares issued pursuant to stock-based compensation plan, shares				46
Cash dividends declared on common stock	(44,058)						(44,058)
Net earnings	86,560						86,560
Other comprehensive income	1,673							1,673
Ending balance at Sep. 30, 2017	1,076,464			$ 572,685			491,935	11,844
Ending balance, shares at Sep. 30, 2017				110,157
Beginning balance at Dec. 31, 2017	1,069,266			$ 573,453			494,361	1,452
Beginning balance, shares at Dec. 31, 2017				110,185
Cumulative adjustment upon adoption of ASU 2018-02							(356)	356
Repurchase of common stock	(988)			$ (988)
Repurchase of common stock, shares				(42)
Issuance of common stock for acquisition			$ 722,767			$ 722,767
Issuance of common stock for acquisition, shares						29,842
Exercise of stock options	1,504			$ 1,504
Exercise of stock options, shares				145
Shares issued pursuant to stock-based compensation plan	2,316			$ 2,316
Shares issued pursuant to stock-based compensation plan, shares				205
Cash dividends declared on common stock	(50,506)						(50,506)
Net earnings	108,844						108,844
Other comprehensive income	(34,623)							(34,623)
Ending balance at Sep. 30, 2018	$ 1,818,580			$ 1,299,052			$ 552,343	$ (32,815)
Ending balance, shares at Sep. 30, 2018				140,335