Intangible Assets and Liabilities Estimated Future Annual Amortization Expense (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Intangible Assets [Abstract]
2018 (amount remaining at June 30, 2018)	$ 38,786
2019	72,012
2020	52,076
2021	36,469
2022	26,282
Beyond 2022	64,753
Total intangible assets subject to amortization (accretion)	290,378	$ 95,228
2018 (amount remaining at June 30, 2018)	(2,609)
2019	(8,233)
2020	(8,028)
2021	(1,963)
2022	(458)
Beyond 2022	0
Intangible liabilities, Net	(21,291)	$ 0
2018 (amount remaining at June 30, 2018)	36,177
2019	63,779
2020	44,048
2021	34,506
2022	25,824
Beyond 2022	64,753
Total intangible assets (liabilities), net	$ 269,087