Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Jan. 01, 2019
New Accounting Pronouncements
Lease expenses	$ 111,549
Operating lease liabilities	522,194
Operating lease maturity payments
2019	3,612,041
2020	3,329,392
2021	2,971,303
2022	2,586,127
2023	2,116,053
Thereafter	5,623,425
Total	$ 20,238,341
Minimum
New Accounting Pronouncements
Discount rate	3.97%
Maximum
New Accounting Pronouncements
Discount rate	5.52%
Accounting Standards Update 2016-02 | Restatement Adjustment
New Accounting Pronouncements
Right-of use assets for operating leases				$ 524,000
Operating lease liabilities				$ 524,000
Accounting Standards Update 2016-02 | Proforma Adjustment
New Accounting Pronouncements
Lease expenses		$ 11,300	$ 45,000