Earnings per Share (Schedule Of Reconciliation Of Basic Earnings Per Share To Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net income (loss)	$ (589,681)	$ 22,477
Weighted average common shares outstanding Class A, B and C (in shares)	452,871,000	449,749,000
Effect of dilutive securities Class A, B, and C (in shares)	0	3,481,000
Weighted average common shares and dilutive securities outstanding Class A, B, and C (in shares)	452,871,000	453,230,000
Basic net income (loss) per share of Class A, B and C common stock (in dollars per share)	$ (1.30)	$ 0.05
Diluted net income (loss) per share of Class A, B and C common stock (in dollars per share)	$ (1.30)	$ 0.05
Antidilutive securities	0	4,100,000