Recently Issued Accounting Standards (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets - operating	$ 63,855
Right-of-use liabilities - operating	60,636
Cumulative effect on retained earnings	$ 3,270		$ 50,009
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets - operating		$ 51,400
Right-of-use liabilities - operating		$ 47,400
Impact of adoption Higher/(Lower) | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earnings				$ 17,300