Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Balance		$ 662,571	$ 622,501	$ 660,417	$ 616,030
Current period other comprehensive income (loss):
Total current period other comprehensive (loss) income		(2,853)	(3,317)	(2,570)	(1,708)
Balance		666,637	635,371	666,637	635,371
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance		(12,914)	(7,708)	(14,168)	(7,638)
Reclassification of stranded tax effects due to adoption of accounting principle	[1]				(1,307)
Adjusted beginning balance						$ (8,945)
Current period other comprehensive income (loss):
Other comprehensive income (loss) before reclassifications		(1,304)	(3,561)	(50)	(1,983)
Amounts reclassified from accumulated other comprehensive (loss) income		0
Effect of taxes	[2]	163	195	163	(146)
Total current period other comprehensive (loss) income		(1,141)	(3,366)	113	(2,129)
Balance		(14,055)	(11,074)	(14,055)	(11,074)
Gain on Sale of Interest Rate Hedge Agreement
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	[3]	2,031	2,563	2,164	2,158
Reclassification of stranded tax effects due to adoption of accounting principle	[1],[3]				478
Adjusted beginning balance	[3]					2,636
Current period other comprehensive income (loss):
Other comprehensive income (loss) before reclassifications	[3]	0
Amounts reclassified from accumulated other comprehensive (loss) income	[3]	(180)	(180)	(360)	(300)
Effect of taxes	[2],[3]	47	48	94	95
Total current period other comprehensive (loss) income	[3]	(133)	(132)	(266)	(205)
Balance	[3]	1,898	2,431	1,898	2,431
Change in Fair Value of Interest Rate Hedge Agreements
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	[4],[5]	(1,385)	886	(547)	441
Adjusted beginning balance	[4],[5]					441
Current period other comprehensive income (loss):
Other comprehensive income (loss) before reclassifications	[4],[5]	(2,173)	181	(3,337)	626
Amounts reclassified from accumulated other comprehensive (loss) income	[4],[5]	31		54
Effect of taxes	[2],[4],[5]	563		866
Total current period other comprehensive (loss) income	[4],[5]	(1,579)	181	(2,417)	626
Balance	[4],[5]	(2,964)	1,067	(2,964)	1,067
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance		(12,268)	(4,259)	(12,551)	(5,039)
Reclassification of stranded tax effects due to adoption of accounting principle	[1]				(829)
Adjusted beginning balance						$ (5,868)
Current period other comprehensive income (loss):
Other comprehensive income (loss) before reclassifications		(3,477)	(3,380)	(3,387)	(1,357)
Amounts reclassified from accumulated other comprehensive (loss) income		(149)	(180)	(306)	(300)
Effect of taxes	[2]	773	243	1,123	(51)
Total current period other comprehensive (loss) income		(2,853)	(3,317)	(2,570)	(1,708)
Balance		$ (15,121)	$ (7,576)	$ (15,121)	$ (7,576)

[1] The Company has adjusted the balance at December 31, 2017 of accumulated other comprehensive loss for the stranded tax effects caused by the enactment of the Tax Cuts and Jobs Act of 2017 (the “Tax Act”).

[2] The Company’s effective tax rate for the three months ended June 30, 2019 and 2018 was 26.2% and 26.6%, respectively, and 22.9% and 24.7% for the six months ended June 30, 2019 and 2018, respectively.

[3] Represents the unamortized value of an interest rate hedge agreement, designated as a cash flow hedge, which was sold on December 1, 2016. The fair value of the interest rate hedge agreement, at the date of the sale, was recorded in other comprehensive income, net of tax, and is being reclassified to interest expense when earnings are impacted by the hedged items and as interest payments are made on the Credit Facility from January 31, 2018 to January 31, 2023.

[4] Represents the change in fair value of interest rate hedge agreements designated as a cash flow hedge.  The fair value of the interest rate hedge agreements was recorded in other comprehensive income and will be reclassified to interest expense when earnings are impacted by the hedged items and as interest payments are made on the Credit Facility from August 31, 2018 to August 31, 2023.

[5] The fair value of the fixed interest rate swap is included in other liabilities on the June 30, 2019 consolidated balance sheet.