Acquisition of Business (Details) - USD ($) $ in Thousands	3 Months Ended								10 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Nov. 09, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
REVENUES	$ 399,358	$ 404,146	$ 377,794	$ 389,277	$ 403,351	$ 366,073	$ 334,576	$ 348,183		$ 1,570,575	$ 1,452,183	$ 892,345
Goodwill	395,974				395,974					395,974	395,974	390,745
Business Combination, Acquisition Related Costs										0	373	5,264
Long-term Debt	1,479,077				1,484,384					1,479,077	1,484,384
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed									$ 5,300
Pro Forma [Member]
Business Acquisition [Line Items]
Depreciation									10,000
REVENUES												1,320,234
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax												$ 88,454
Omni Air [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents									4,693
Business Combination, Acquired Receivables, Estimated Uncollectible									63,041
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets									8,366
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets									7,836
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill									140,000
Goodwill									353,466
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment									328,869
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities									(32,646)
Business Combination, Contingent Consideration, Liability									(5,950)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net									867,675
Payments to Acquire Businesses, Gross									867,700
Revolving Credit Facility [Member]
Business Acquisition [Line Items]
Long-term Debt	$ 140,000				$ 632,900					$ 140,000	$ 632,900
Line of Credit Facility, Accordion Feature Amount									180,000
Senior Notes 2nd Term Loan [Member]
Business Acquisition [Line Items]
Long-term Debt									$ 675,000