Consolidated Statement of Shareholders' Equity - 9 months ended Sep. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Restricted Shares	Restricted Shares Common Stock	Restricted Shares Treasury Stock	ASB Financial Corp. [Member] Common Stock
Balance, December 31, 2017 at Dec. 31, 2017	$ 458,592	$ 345,412	$ 134,362	$ (5,215)	$ (15,967)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Amounts reclassified out of retained earnings, net of tax, per ASU 2014-09 | Accounting Standards Update 2014-09 [Member]			(3,055)
Net income	32,358		32,358
Other comprehensive income (loss), net of tax	5,020
Other comprehensive income (loss), net of tax	(10,355)			(15,375)
Cash dividends declared	(15,709)		(15,709)
Exercise of stock appreciation rights	0	(2)			2
Reissuance of treasury stock for deferred compensation plan for Boards of Directors						$ 0	$ (2,674)	$ 2,674
Reissuance of treasury stock for deferred compensation plan for Boards of Directors	46				46
Repurchase of treasury stock in connection with employee incentive plan and under compensation plan for Boards of Directors	(1,271)				(1,271)
Common shares issued under dividend reinvestment plan	497	497
Common shares issued under compensation plan for Boards of Directors	242	85			157
Common shares issued under employee stock purchase plan	189	68			121
Share-based Compensation	1,858	1,858
Issuance of common shares related to acquisition of ASB Financial Corp. (ASB)	40,898								$ 40,898
Balance, September 30, 2018 at Sep. 30, 2018	$ 504,290	$ 386,142	$ 152,976	$ (20,590)	$ (14,238)