Credit Agreement (Details) In Thousands, unless otherwise specified	1 Months Ended			1 Months Ended	9 Months Ended
	Jun. 30, 2013 Credit Agreement USD ($)	Sep. 30, 2013 Credit Agreement USD ($)	Mar. 31, 2013 Credit Agreement USD ($)	Nov. 12, 2013 Credit Agreement Subsequent Event USD ($)	Sep. 30, 2013 Credit Agreement Subsequent Event USD ($)	Sep. 30, 2013 China Credit Agreement USD ($)	Sep. 30, 2013 China Credit Agreement CNY	Sep. 30, 2013 China Credit Agreement Subsequent Event USD ($)
Notes Payable and Long-Term Debt
Increase in additional borrowings allowed per amendment	$ 12,500
Additional borrowing related to headquarters allowed under Credit Agreement covenants prior to amendment	80,000		75,000
Amount allowed to be borrowed in the third and fourth quarters						10,000	60,000
Amount borrowed				31,000	3,000
Outstanding borrowings		239,000		243,000		7,000		10,000
Weighted average interest rate (as a percent)		1.69%
Outstanding letters of credit		200
Amount unused balance under the Credit Agreement		160,800
Current borrowing capacity		110,600
Amount allowed to be borrowed in the first and second quarters						3,300	20,000
Effective interest rate on debt						6.00%	6.00%
Percentage of facility amount in USD guaranteed						110.00%	110.00%
Repaid on borrowings				$ 27,000