CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Pension and other postretirement adjustments, tax	$ 62	$ 578	$ 435	$ 438
Amortization of forward starting swaps, tax	$ 623	$ 351	$ 359	$ 361
Issuance of common stock from performance share units and exercise of stock options (in shares)	145,263	131,757	169,785	264,090
Issuance of common stock from exercise of stock options and deferred compensation plans, tax amount	$ 594	$ 3,061	$ 679	$ 3,415
Purchase of common stock (in shares)	9,600	866,823	19,143	369,810
Cash dividends declared, per common share outstanding (in dollars per share)	$ 1.00		$ 1.00