Leased Properties - Future Lease Payments (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Leases [Abstract]
April 1, 2019 through December 31, 2019	$ 232,216
2020	251,630
2021	184,486
2022	131,885
2023	90,017
Thereafter	213,847
Total undiscounted future minimum lease payments	1,104,081
Less: Difference between undiscounted lease payments and discounted operating lease liabilities	125,175
Total operating lease liabilities	$ 978,906