Revenues - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue	$ 10,810		$ 10,390
Capital Units, Value	338,159		$ 381,103
Deferred revenue recognized	$ 7,500
Document Period End Date	Mar. 31, 2020
Deferred revenue recognized. billed prior period	$ 700	$ 600
Contract With Customer, Asset, Revenue Recognized	200
Services revenue	127,854	134,497
Operating Lease, Lease Income	93,200	94,300
Revenue, Remaining Performance Obligation, Amount	2,344,000
Shortfall Payments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue shortfalls billed	300
Service, Other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Services revenue	$ 34,700	$ 40,200