Debt (Details) $ in Thousands		12 Months Ended
	Oct. 30, 2015 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Nov. 30, 2012 USD ($)
Short-term Debt [Line Items]
Current Fiscal Year End Date		--12-31
Credit facility		$ 0	$ 18,831
Interest Expense, Debt		$ 1,100	500	$ 200
Bank of America, N.A. [Member] | Credit Agreement [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					$ 75,000
Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Debt Instrument, Term	5 years
Revolving Credit Facility [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 150,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.25%
Line of Credit Facility, Optional Additional Borrowing Capacity	75,000
Revolving Credit Facility [Member] | Credit Agreement [Member]
Short-term Debt [Line Items]
Remaining borrowing capacity under line of credit		$ 122,300
Debt Instrument, Interest Rate, Effective Percentage		0.00%
Amount outstanding on line of credit		$ 0
Letters of Credit Outstanding, Amount		$ 3,300
Revolving Credit Facility [Member] | Minimum [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Fixed Charge Coverage Ratio		1.0
Revolving Credit Facility [Member] | Bank of America, N.A. [Member] | Credit Agreement [Member]
Short-term Debt [Line Items]
Amount outstanding on line of credit			18,800
Letters of Credit Outstanding, Amount			$ 3,300
Swingline Loans [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 25,000
Line of Credit Facility, Current Borrowing Capacity, Percent of Eligible Billed Accounts Receivable	85.00%
Line of Credit Facility, Current Borrowing Capacity, Percent of Eligible Unbilled Accounts Receivable Less Certain Reserves	80.00%
Swingline Loans [Member] | Maximum [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity, Percent of Eligible Unbilled Accounts Receivable Less Certain Reserves	30.00%
Letter of Credit [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 15,000
UNITED STATES | Revolving Credit Facility [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	135,000
CANADA | Revolving Credit Facility [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 15,000
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | Minimum [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.25%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | Maximum [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.75%
Federal Funds Effective Swap Rate [Member] | Revolving Credit Facility [Member] | Minimum [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate		0.25%
Federal Funds Effective Swap Rate [Member] | Revolving Credit Facility [Member] | Maximum [Member] | October 2015 Line of Credit [Member]
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate		0.75%