Leases - Lease Obligations (Details) $ in Thousands	Mar. 31, 2018 USD ($)
Minimum Rental Revenues
2018	$ 125,069
2019	169,873
2020	155,238
2021	135,874
2022	116,972
Thereafter	527,122
Total	1,230,148
Minimum Rental Payments
2018	4,546
2019	4,565
2020	4,256
2021	4,364
2022	4,400
Thereafter	183,911
Total	$ 206,042