Intangible Assets and Liabilities Estimated Future Annual Amortization Expense (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Intangible Assets [Abstract]
2019 (amount remaining at June 30, 2019)	$ 36,345
2020	53,126
2021	37,772
2022	27,407
2023	19,825
Beyond 2023	47,292
Total intangible assets subject to amortization (accretion)	221,767	$ 254,483
2019 (amount remaining at June 30, 2019)	(4,117)
2020	(8,028)
2021	(1,963)
2022	(459)
2023	0
Beyond 2023	0
Intangible liabilities, Net	(14,567)	$ (18,683)
2019 (amount remaining at June 30, 2019)	32,228
2020	45,098
2021	35,809
2022	26,948
2023	19,825
Beyond 2023	47,292
Total intangible assets (liabilities), net	$ 207,200