CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
Change in the fair value of interest rate swap contracts, income tax (in dollars)	$ 1,574	$ 3,471	$ 20
Pension and other post-retirement liabilities, income tax (in dollars)	7,239	2,056	305
Exercise of stock options, tax benefit (in dollars)	$ 1,668	$ 479
Exercise of stock options, shares	878,658	790,596
Shares issued under stock incentive plan	762,004	50,446	40,818
Shares issued under employee stock purchase plan	2,567	3,251	6,716
Shares issued to Board of Directors in lieu of cash	2,739	3,603	7,314
Stock-based compensation, forfeitures	30,000	12,000	65,735
Cash dividend (in dollars per share)	$ 0.36	$ 0.12	$ 0.18
Purchase of common stock, shares	768,780	869,065	180,833