Summary of Accounting Policies (Details 2) (USD $)							12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013 Foreign subsidiaries	Dec. 31, 2012 Foreign subsidiaries	Dec. 31, 2013 Labor force concentration risk Collective bargaining agreements	Dec. 31, 2013 Labor force concentration risk Collective bargaining agreement that expired on July 31, 2013	Dec. 31, 2013 Labor force concentration risk Collective bargaining agreements that expire in 2014
Summary of Accounting Policies
Undistributed earnings of non-U.S. subsidiaries	$ 77,400,000
Summary of Accounting Policies
Percentage of labor force covered							28.00%	5.00%	5.00%
Cash deposits
Cash deposits with U.S. financial institutions in excess of federally insured limits	0
Cash and cash equivalents	$ 32,942,000	$ 18,161,000	$ 13,574,000	$ 33,992,000	$ 27,600,000	$ 16,000,000