CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Pension and other postretirement adjustments, tax	$ 435	$ 438	$ 457	$ 505
Amortization of forward starting swaps, tax	$ 359	$ 361	$ 368	$ 371
Issuance of common stock from performance share units and exercise of stock options (in shares)	169,785	264,090	96,981	227,932
Issuance of common stock from exercise of stock options and deferred compensation plans, tax amount	$ 679	$ 3,415	$ 351	$ 2,934
Purchase of common stock (in shares)	19,143	369,810	147,490	0
Cash dividends declared, per common share outstanding (in dollars per share)	$ 1.00	$ 0	$ 0.86	$ 0