Basis of Presentation and Recently Adopted Accounting Pronouncements - Narrative (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 liabilities	$ 332,140
Operating lease ROU assets	$ 316,831		$ 0
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities		$ 358,000
Operating lease ROU assets		$ 358,000