CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Tax benefit (expense) on change in retirement obligations, tax	$ 1,553	$ 3,076	$ 239
Tax benefit from change on derivatives designated as cash flow hedges, tax	$ 1,445	$ 1,469	$ 2,445
Issuance of common stock from issuance of unvested shares, exercise of stock options and deferred compensation plans (in shares)	696,133	583,385	577,591
Repurchase of common stock (in shares)	388,953	1,300,000	266,000
Deferred compensation paln, tax	$ 5,493	$ 4,267	$ 6,027
Cash dividends declared, per common share outstanding (in dollars per share)	$ 2.00	$ 1.72	$ 1.48