Leases - Right of use assets and lease liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
Leases [Abstract]
Operating lease assets	$ 253,336	$ 282,000
Finance lease assets	1,062
Total right-of-use assets	254,398
Operating lease liabilities, current	61,006	72,000
Operating lease liabilities, noncurrent	217,060	$ 222,000
Finance lease liabilities, current	471
Finance lease liabilities, noncurrent	700
Total lease liabilities	$ 279,237