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		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings (Loss) Per Share [Line Items]
Net income (loss) to shareholders	$ (259,141)	$ 83,796	$ (39,612)	$ 322,963
Adjustment of redeemable noncontrolling interests	(3,298)	(4,928)	(23,582)	(10,909)
Adjusted net income (loss) to shareholders	$ (262,439)	$ 78,868	$ (63,194)	$ 312,054
Basic common shares outstanding	13,947	14,033	13,974	14,013
Diluted shares outstanding	13,990	14,085	14,018	14,079
Basic net income (loss) per share	$ (18.82)	$ 5.62	$ (4.52)	$ 22.27
Diluted net income (loss) per share	$ (18.82)	$ 5.60	$ (4.52)	$ 22.16
Stock Options [Member]
Earnings (Loss) Per Share [Line Items]
Dilutive potential common shares	1	3	2	4
Restricted Stock Units (RSUs) [Member]
Earnings (Loss) Per Share [Line Items]
Dilutive potential common shares	42	49	42	62