Leases (Future Minimum Lease Payments for Operating Leases) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	[1]
Leases
April 1, 2019, to December 31, 2019	$ 236,772
2020	301,981
2021	273,648
2022	248,566
2023	218,016
Thereafter	1,175,611
Total operating lease payments	2,454,594
Less: present value discount	528,678
Total operating lease liabilities	1,925,916
Less: current portion of operating lease liabilities	296,605	$ 0
Operating lease liabilities, less current portion	1,629,311	$ 0
Related parties [Member]
Leases
April 1, 2019, to December 31, 2019	3,561
2020	3,988
2021	3,521
2022	2,763
2023	2,540
Thereafter	3,544
Total operating lease payments	19,917
Less: present value discount	2,180
Total operating lease liabilities	17,737
Less: current portion of operating lease liabilities	4,598
Operating lease liabilities, less current portion	13,139
Non-related parties [Member]
Leases
April 1, 2019, to December 31, 2019	233,211
2020	297,993
2021	270,127
2022	245,803
2023	215,476
Thereafter	1,172,067
Total operating lease payments	2,434,677
Less: present value discount	526,498
Total operating lease liabilities	1,908,179
Less: current portion of operating lease liabilities	292,007
Operating lease liabilities, less current portion	$ 1,616,172

[1] The balance sheet at December 31, 2018, has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by United States generally accepted accounting principles for complete financial statements.