Leases Right of use assets and lease liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
Leases [Abstract]
Operating lease assets	$ 312,262	$ 282,000
Finance lease assets	1,504
Total right-of-use assets		313,766
Operating lease liabilities, current	67,428	(72,000)
Operating lease liabilities, noncurrent	255,190	(222,000)
Finance lease liabilities, current	1,009
Finance lease liabilities, noncurrent	$ 947
Total lease liabilities		$ 324,574