CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Statement of Stockholders' Equity [Abstract]
Pension and other postretirement adjustments, tax	$ 1,753
Amortization of forward starting swaps, tax	$ 1,845
Issuance of common stock from performance share units and exercise of stock options (in shares) | shares	470,104
Issuance of common stock from exercise of stock options and deferred compensation plans, tax amount	$ 5,579
Repurchase of common stock (in shares) | shares	222,000
Cash dividends declared, per common share outstanding (in dollars per share) | $ / shares	$ 1.11