Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2017
Income Taxes [Line Items]
Effective tax rate (as a percent)	23.70%		12.00%	20.50%	11.60%
Income tax (expense) benefit	$ (9,576,000)		$ 42,900,000	$ (14,710,000)	$ 40,712,000
Goodwill impairment, tax benefit			50,400,000		50,400,000
Income taxes, statutory rate				21.00%		35.00%
Goodwill, Impairment Loss	$ 0	$ 0	379,863,000		379,863,000
Goodwill yielding permanent differences between book income and taxable income			$ 209,500,000		$ 209,500,000
Excluding Impact Of Goodwill Impairment Charge [Member]
Income Taxes [Line Items]
Effective tax rate (as a percent)			34.70%		34.00%