Long-Term Debt (Narrative - North America) (Details)	Apr. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Nov. 07, 2016 USD ($)
Revolving credit facility
Line of Credit Facility
Line of credit facility, amount outstanding		$ 65,323,000	$ 74,008,000
Term loan
Line of Credit Facility
Line of credit facility, amount outstanding		25,000,000	$ 0
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company
Line of Credit Facility
Line of credit facility, maximum borrowing capacity				$ 195,000,000
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Revolving credit facility
Line of Credit Facility
Line of credit facility, maximum borrowing capacity	$ 140,000,000
Potential increase to borrowing capacity	$ 50,000,000
Line of credit facility, current borrowing capacity		73,841,000
Debt instrument term	5 years
Maximum growth leverage ratio	3.25
Maximum growth leverage ratio during acquisition period	3.50
Minimum consolidated fixed charge coverage ratio	1.25
Minimum working capital to revolving facility usage ratio	1.40
Liquidity covenant	$ 25,000,000
Acquisition consideration threshold, per acquisition	50,000,000
Aggregate acquisition threshold for four consecutive periods where acquisitions occurred	50,000,000
Aggregate acquisition consideration threshold	100,000,000
Line of credit facility, amount outstanding		$ 836,000
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Revolving credit facility | Foreign Sublimit
Line of Credit Facility
Line of credit facility, maximum borrowing capacity	$ 25,000,000
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Revolving credit facility | Euro-rate
Line of Credit Facility
Debt instrument, basis spread on variable rate	1.00%
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Revolving credit facility | Euro-rate | Minimum
Line of Credit Facility
Debt instrument, basis spread on variable rate	1.25%
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Revolving credit facility | Euro-rate | Maximum
Line of Credit Facility
Debt instrument, basis spread on variable rate	2.25%
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Revolving credit facility | Base Rate | Minimum
Line of Credit Facility
Debt instrument, basis spread on variable rate	0.25%
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Revolving credit facility | Base Rate | Maximum
Line of Credit Facility
Debt instrument, basis spread on variable rate	1.25%
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Revolving credit facility | Overnight Bank Funding Rate
Line of Credit Facility
Debt instrument, basis spread on variable rate	0.50%
PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A., Citizens Bank of Pennsylvania, and Branch Banking and Trust Company | Term loan | Term Loan
Line of Credit Facility
Line of credit facility, current borrowing capacity	$ 25,000,000