The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Intangible Assets, by category
Gross Carrying Amount	$ 574,570		$ 574,570		$ 412,657
Accumulated Amortization	125,125		125,125		113,575
Amortization expense for intangible assets	8,352	$ 1,901	14,270	$ 3,840
Estimated amortization expense for next 5 years
2020	31,200		31,200
2021	32,300		32,300
2022	31,600		31,600
2023	31,600		31,600
2024	31,100		31,100
Customer related
Intangible Assets, by category
Gross Carrying Amount	165,770		165,770		143,996
Accumulated Amortization	101,512		101,512		99,327
Permits
Intangible Assets, by category
Gross Carrying Amount	308,432		308,432		170,322
Accumulated Amortization	11,028		11,028		4,694
Patents
Intangible Assets, by category
Gross Carrying Amount	185		185		249
Accumulated Amortization	130		130		168
Technology related
Intangible Assets, by category
Gross Carrying Amount	36,411		36,411		36,467
Accumulated Amortization	6,966		6,966		5,635
Trade names
Intangible Assets, by category
Gross Carrying Amount	31,525		31,525		31,719
Accumulated Amortization	3,452		3,452		2,182
Air rights
Intangible Assets, by category
Gross Carrying Amount	26,139		26,139		26,139
Accumulated Amortization	743		743		411
Other
Intangible Assets, by category
Gross Carrying Amount	3,608		3,608		3,765
Accumulated Amortization	1,138		1,138		1,158
Noncompete Agreements
Intangible Assets, by category
Gross Carrying Amount	2,500		2,500		$ 0
Accumulated Amortization	$ 156		$ 156