Significant Accounting Policies - Impairment of Long-Lived Assets (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of definite-lived assets		$ 7,100,000
Asset impairments			$ 10,155,000	$ 0	$ 0
HST
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment charges		9,700,000
Operating lease, impairment	$ 400,000	600,000
HST | Property, plant and equipment
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairments		2,000,000.0
HST | Customer relationships
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of definite-lived assets		6,100,000
HST | Unpatented technology
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of definite-lived assets		$ 1,000,000.0