Intangible Assets - (Intangibles Subject to Amortization) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 553,295	$ 547,988
Accumulated amortization	(183,714)	(156,009)
Net carrying amount	369,581	391,979
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	408,267	408,267
Accumulated amortization	(112,192)	(95,167)
Net carrying amount	296,075	313,100
Other amortizable intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	145,028	139,721
Accumulated amortization	(71,522)	(60,842)
Net carrying amount	$ 73,506	$ 78,879