Intangible Assets Estimated Future Annual Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Intangible Assets [Abstract]
2018 (amount remaining at March 31, 2018)	$ 58,564
2019	72,345
2020	52,265
2021	36,649
2022	26,317
Beyond 2022	65,244
Total intangible assets subject to amortization (accretion)	311,384	$ 95,228
2018 (amount remaining at March 31, 2018)	(3,913)
2019	(8,233)
2020	(8,028)
2021	(1,963)
2022	(459)
Beyond 2022	0
Finite-Lived Intangible Liabilities, Net	(22,596)	$ 0
2018 (amount remaining at March 31, 2018)	54,651
2019	64,112
2020	44,237
2021	34,686
2022	25,858
Beyond 2022	65,244
Total intangible assets subject to amortization (accretion)	$ 288,788