Shareholders' Equity (Schedule Of Net Income (Loss) Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Line Items]
Net income to shareholders	$ 205,637	$ 409,438	$ 1,279,362	$ 623,363
Adjustment of redeemable noncontrolling interests	(12,221)	(12,035)	9,464	(6,621)
Adjusted net income to shareholders	$ 193,416	$ 397,403	$ 1,288,826	$ 616,742
Basic common shares outstanding	13,849	13,917	13,870	13,925
Diluted shares outstanding	13,864	13,943	13,882	13,949
Basic net income per share	$ 13.97	$ 28.56	$ 92.92	$ 44.29
Diluted net income per share	$ 13.95	$ 28.50	$ 92.84	$ 44.21
Restricted Stock Units (RSUs) [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares	15	26	12	24