Long-Term Indebtedness (Details)				3 Months Ended
	Apr. 27, 2016 USD ($)	Mar. 20, 2015 USD ($)	Feb. 24, 2014 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2015 USD ($)	Mar. 03, 2015 USD ($)
Line of Credit Facility
Long-term indebtedness				$ 49,920,000	$ 49,910,000	$ 49,955,000
Line of Credit
Line of Credit Facility
Debt outstanding at period end				0
Remaining availability under the facilities				$ 197,400,000
Maximum leverage ratio				2.5
JPMorgan Chase Bank And Wells Fargo Bank | Line of Credit
Line of Credit Facility
Maximum borrowings under line of credit			$ 75,000,000				$ 100,000,000
Potential increase in line of credit borrowing capacity			25,000,000
Letters of credit outstanding amount				$ 2,600,000
Remaining availability under the facilities				$ 97,400,000
JPMorgan Chase Bank And Wells Fargo Bank | Line of Credit | Prime Rate
Line of Credit Facility
Basis spread on variable rate				1.00%
Minimum stated interest rate				1.50%
JPMorgan Chase Bank And Wells Fargo Bank | Line of Credit | Prime Rate | Minimum
Line of Credit Facility
Basis spread on variable rate				0.75%
JPMorgan Chase Bank And Wells Fargo Bank | Line of Credit | Prime Rate | Maximum
Line of Credit Facility
Basis spread on variable rate				1.00%
JPMorgan Chase Bank And Wells Fargo Bank | Line of Credit | LIBOR
Line of Credit Facility
Basis spread on variable rate				1.75%
JPMorgan Chase Bank And Wells Fargo Bank | Line of Credit | LIBOR | Minimum
Line of Credit Facility
Basis spread on variable rate				1.75%
JPMorgan Chase Bank And Wells Fargo Bank | Line of Credit | LIBOR | Maximum
Line of Credit Facility
Basis spread on variable rate				2.00%
Prudential Investment Management Inc | Line of Credit
Line of Credit Facility
Remaining availability under the facilities			$ 150,000,000
Period after request is issued, by company, for interest payable rate to be determined by Prudential			5 days
Long-term indebtedness		$ 50,000,000
Debt Instrument, Term		5 years
Interest rate during period				3.35%
Prudential Investment Management Inc | Line of Credit | Maximum
Line of Credit Facility
Maturity period of Promissory Notes			12 years
Subsequent Event | JPMorgan Chase Bank, N.A., Wells Fargo Bank, N.A., Bank of America, N.A., and 1st Source Bank | Line of Credit
Line of Credit Facility
Maximum borrowings under line of credit	$ 200,000,000.0
Maximum draw capacity in approved foreign currencies	50,000,000.0
Additional maximum borrowing capacity upon approval	$ 125,000,000.0
Option One | Subsequent Event | JPMorgan Chase Bank, N.A., Wells Fargo Bank, N.A., Bank of America, N.A., and 1st Source Bank | Line of Credit | LIBOR
Line of Credit Facility
Basis spread on variable rate	1.00%
Option One | Subsequent Event | JPMorgan Chase Bank, N.A., Wells Fargo Bank, N.A., Bank of America, N.A., and 1st Source Bank | Line of Credit | LIBOR | Minimum
Line of Credit Facility
Debt instrument, additional margin interest rate	0.00%
Option One | Subsequent Event | JPMorgan Chase Bank, N.A., Wells Fargo Bank, N.A., Bank of America, N.A., and 1st Source Bank | Line of Credit | LIBOR | Maximum
Line of Credit Facility
Debt instrument, additional margin interest rate	0.625%
Option One | Subsequent Event | JPMorgan Chase Bank, N.A., Wells Fargo Bank, N.A., Bank of America, N.A., and 1st Source Bank | Line of Credit | Federal Funds Effective Rate
Line of Credit Facility
Basis spread on variable rate	0.50%
Option Two | Subsequent Event | JPMorgan Chase Bank, N.A., Wells Fargo Bank, N.A., Bank of America, N.A., and 1st Source Bank | Line of Credit | LIBOR | Minimum
Line of Credit Facility
Basis spread on variable rate	1.00%
Option Two | Subsequent Event | JPMorgan Chase Bank, N.A., Wells Fargo Bank, N.A., Bank of America, N.A., and 1st Source Bank | Line of Credit | LIBOR | Maximum
Line of Credit Facility
Basis spread on variable rate	1.625%