Leases (Summary of Lease Assets and Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease asset	$ 151,801	$ 170,056
Finance lease asset	13,453	15,713
Total lease assets	165,254	185,769
Operating lease liability, current	30,011	30,171
Finance lease liability, current	3,508	3,788
Total lease liabilities, current	33,519	33,959
Operating lease liability, noncurrent	181,032	193,570
Finance lease liability, noncurrent	28,517	17,477
Total lease liabilities, noncurrent	209,549	211,047
Total lease liabilities	$ 243,068	$ 245,006