Net Income (Loss) per Share (Schedule Of Net Income (Loss) Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Line Items]
Net income to shareholders	$ 497,298	$ 278,231	$ 1,073,725	$ 213,925
Adjustment of redeemable noncontrolling interests	3,324	363	21,685	5,414
Adjusted net income (loss) to shareholders	$ 500,622	$ 278,594	$ 1,095,410	$ 219,339
Basic common shares outstanding	13,866	13,925	13,881	13,929
Diluted shares outstanding	13,878	13,950	13,893	13,953
Basic net income (loss) per share	$ 36.10	$ 20.01	$ 78.91	$ 15.75
Diluted net income (loss) per share	$ 36.07	$ 19.97	$ 78.85	$ 15.72
Restricted Stock Units (RSUs) [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares	12	25	12	24