Recent Accounting Developments Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 1,046,262		$ 0
Current maturities of operating leases	128,138		0
Operating leases, less current maturities	895,056		$ 0
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	1,000,000
Current maturities of operating leases	128,100
Operating leases, less current maturities	$ 895,100
Restatement Adjustment [Member] | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ (5,500)