Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Balance		$ 714,551		$ 660,417	$ 616,030
Current period other comprehensive (loss) income:
Total current period other comprehensive income (loss)		(1,962)		407	(6,683)
Balance		746,961		714,551	660,417
Cumulative-Effect Adjustments for Adoption of Accounting Principle
Current period other comprehensive (loss) income:
Balance		(513)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance		(10,995)		(14,168)	(7,638)
Adjusted beginning balance					(8,945)
Current period other comprehensive (loss) income:
Other comprehensive income (loss) before reclassifications		4,141		2,338	(4,711)
Amounts reclassified from accumulated other comprehensive income		0	[1]	0	0
Effect of taxes	[2]	(356)		835	(512)
Total current period other comprehensive income (loss)		3,785		3,173	(5,223)
Balance		(7,210)		(10,995)	(14,168)
Foreign Currency Translation Adjustments | Cumulative-Effect Adjustments for Adoption of Accounting Principle
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	[3]				(1,307)
Gain on Sale of Interest Rate Hedge Agreement
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	[4]	1,634		2,164	2,158
Adjusted beginning balance	[4]				2,636
Current period other comprehensive (loss) income:
Other comprehensive income (loss) before reclassifications	[4]	0		0	0
Amounts reclassified from accumulated other comprehensive income	[4]	(720)	[1]	(720)	(660)
Effect of taxes	[2],[4]	182		190	188
Total current period other comprehensive income (loss)	[4]	(538)		(530)	(472)
Balance	[4]	1,096		1,634	2,164
Gain on Sale of Interest Rate Hedge Agreement | Cumulative-Effect Adjustments for Adoption of Accounting Principle
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	[3],[4]				478
Changes in Fair Value of Interest Rate Hedge Agreements
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	[5],[6]	(2,783)		(547)	441
Adjusted beginning balance	[5],[6]				441
Current period other comprehensive (loss) income:
Other comprehensive income (loss) before reclassifications	[5],[6]	(9,867)		(3,362)	(1,184)
Amounts reclassified from accumulated other comprehensive income	[5],[6]	2,751	[1]	333	(12)
Effect of taxes	[2],[5],[6]	1,907		793	208
Total current period other comprehensive income (loss)	[5],[6]	(5,209)		(2,236)	(988)
Balance	[5],[6]	(7,992)		(2,783)	(547)
Changes in Fair Value of Interest Rate Hedge Agreements | Cumulative-Effect Adjustments for Adoption of Accounting Principle
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	[3],[5],[6]				0
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance		(12,144)		(12,551)	(5,039)
Adjusted beginning balance					(5,868)
Current period other comprehensive (loss) income:
Other comprehensive income (loss) before reclassifications		(5,726)		(1,024)	(5,895)
Amounts reclassified from accumulated other comprehensive income		2,031	[1]	(387)	(672)
Effect of taxes	[2]	1,733		1,818	(116)
Total current period other comprehensive income (loss)		(1,962)		407	(6,683)
Balance		$ (14,106)		$ (12,144)	(12,551)
Accumulated Other Comprehensive Loss | Cumulative-Effect Adjustments for Adoption of Accounting Principle
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	[3]				$ (829)

[1] The Company expects to reclassify $0.7 million related to the Gain on Sale of Interest Rate Hedge Agreement, and $3.7 million losses related to the Change in Fair Value of Interest Rate Hedge Agreement from accumulated other comprehensive loss into earnings during the next 12 months.

[2] The Company’s effective tax rate for the years ended December 31, 2020, 2019, and 2018 was 26.4%, 23.6%, and 25.9%, respectively.

[3] The Company has adjusted the balance of accumulated other comprehensive (loss) income at December 3, 2017 after the adoption of ASU 2018-02.

[4] Represents the fair 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 was recorded in other comprehensive income, net of tax, and will be reclassified to earnings when earnings are impacted by the hedged items, as interest payments are made on the Credit Facility from January 31, 2018 to January 31, 2023.

[5] Represents the change in fair value of an interest rate hedge agreements designated as a cash flow hedges.  The fair value of the interest rate hedge agreement was recorded in other comprehensive income and will be reclassified to earnings when earnings are impacted by the hedged items, as interest payments are made on the Credit Facility from August 31, 2018 to February 28, 2025. See additional details of the hedge agreements in Note 12 - Derivative Instruments and Hedging Activities.

[6] The fair value of the interest rate hedge agreements is included in other current and other long-term liabilities on the consolidated balance sheet.