Recent Accounting Developments (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 asset	$ 200,788	$ 208,929	$ 0
Operating lease liability	$ 195,209	204,364
ASC Topic 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset		209,000
Operating lease liability		$ 209,000