Changes in Shareholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Balance			$ 547,779
Net income	11,774	4,698	33,644	8,830
Dividends declared			(14,964)
Changes in equity related to noncontrolling interest in ASC			14
Compensation and benefits paid or payable in Class A Common Stock			1,011
Options exercised			771
Shares issued to Directors			150
Cumulative translation adjustment			(30,696)
Change in pension liability adjustment			1,419
Change in derivative valuation adjustment			343
Balance	539,471		539,471
Common Stock [Member] | Common Class A [Member]
Balance			37
Net income
Dividends declared
Changes in equity related to noncontrolling interest in ASC
Compensation and benefits paid or payable in Class A Common Stock
Options exercised
Shares issued to Directors
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	37		37
Common Stock [Member] | Common Class B [Member]
Balance			3
Net income
Dividends declared
Changes in equity related to noncontrolling interest in ASC
Compensation and benefits paid or payable in Class A Common Stock
Options exercised
Shares issued to Directors
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	3		3
Additional Paid-in Capital [Member]
Balance			416,728
Net income
Dividends declared
Changes in equity related to noncontrolling interest in ASC			(24)
Compensation and benefits paid or payable in Class A Common Stock			1,011
Options exercised			771
Shares issued to Directors			60
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	418,546		418,546
Retained Earnings [Member]
Balance			434,598
Net income			33,652
Dividends declared			(14,964)
Changes in equity related to noncontrolling interest in ASC
Compensation and benefits paid or payable in Class A Common Stock
Options exercised
Shares issued to Directors
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	453,286		453,286
Accumulated Items of Other Comprehensive Income [Member]
Balance			(49,498)
Net income
Dividends declared
Changes in equity related to noncontrolling interest in ASC
Compensation and benefits paid or payable in Class A Common Stock
Options exercised
Shares issued to Directors
Cumulative translation adjustment			(30,703)
Change in pension liability adjustment			1,419
Change in derivative valuation adjustment			343
Balance	(78,439)		(78,439)
Treasury Stock [Member]
Balance			(257,571)
Net income
Dividends declared
Changes in equity related to noncontrolling interest in ASC
Compensation and benefits paid or payable in Class A Common Stock
Options exercised
Shares issued to Directors			90
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	(257,481)		(257,481)
Noncontrolling Interest [Member]
Balance			3,482
Net income			(8)
Dividends declared
Changes in equity related to noncontrolling interest in ASC			38
Compensation and benefits paid or payable in Class A Common Stock
Options exercised
Shares issued to Directors
Cumulative translation adjustment			7
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	$ 3,519		$ 3,519