Leases (Summary of Lease Assets and Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease asset	$ 168,503	$ 170,056
Finance lease asset	27,853	15,713
Total lease assets	196,356	185,769
Operating lease liability, current	30,546	30,171
Finance lease liability, current	3,311	3,788
Total lease liabilities, current	33,857	33,959
Operating lease liability, noncurrent	189,873	193,570
Finance lease liability, noncurrent	29,836	17,477
Total lease liabilities, noncurrent	219,709	211,047
Total lease liabilities	$ 253,566	$ 245,006