Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Interest Rate Swap
Derivatives:
Asset for Swaps		$ 600
Recurring
Financial Assets:
Cash and cash equivalents	$ 302,329	104,162
Restricted cash	10,504	10,517
Other investments	3,279	1,898
Total	316,112	116,577
Financial Liabilities:
Total debt	1,590,260	1,690,731
Total	1,590,260	1,690,731
Recurring | Interest Rate Swap
Derivatives:
Asset for Swaps		572
Derivative Liability	87,725	47,691
Recurring | Level 1
Financial Assets:
Cash and cash equivalents	302,329	104,162
Restricted cash	8,719	9,791
Other investments	0	0
Total	311,048	113,953
Financial Liabilities:
Total debt	0	0
Total	0	0
Recurring | Level 1 | Interest Rate Swap
Derivatives:
Asset for Swaps		0
Derivative Liability	0	0
Recurring | Level 2
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	1,785	726
Other investments	3,279	1,898
Total	5,064	2,624
Financial Liabilities:
Total debt	1,590,260	1,690,731
Total	1,590,260	1,690,731
Recurring | Level 2 | Interest Rate Swap
Derivatives:
Asset for Swaps		572
Derivative Liability	87,725	47,691
Recurring | Level 3
Financial Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Other investments	0	0
Total	0	0
Financial Liabilities:
Total debt	0	0
Total	0	0
Recurring | Level 3 | Interest Rate Swap
Derivatives:
Asset for Swaps		0
Derivative Liability	$ 0	$ 0