Leases (Maturities of Lease Liabilities) (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Operating lease liabilities
Remainder of 2019	$ 62,313
2020	84,415
2021	83,181
2022	79,187
2023	78,382
Thereafter	548,011
Total undiscounted future cash flows	935,489
Less: Imputed interest	(210,019)
Present value of undiscounted future cash flows	725,470
Finance lease liabilities
Remainder of 2019	5,351
2020	8,823
2021	8,868
2022	9,332
2023	9,788
Thereafter	234,658
Total undiscounted future cash flows	276,820
Less: Imputed interest	(109,056)
Present value of undiscounted future cash flows	$ 167,764