Financial Statement Presentation - 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 liability	$ 42,019
Operating lease right-of-use assets	$ 42,174		$ 0
Topic 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liability		$ 44,600
Operating lease right-of-use assets		$ 44,600