Shareholders' Equity (Schedule Of Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Line Items]
Net income to shareholders	$ 197,892	$ 102,519	$ 91,369	$ 190,992	$ 117,595	$ 75,803	$ 40,068	$ 87,716	$ 98,764	$ 65,599	$ 27,756	$ 88,902	$ 582,772	$ 321,182	$ 281,021
Adjustment of redeemable noncontrolling interests													4,144	(8,186)	1,963
Adjusted net income to shareholders													$ 586,916	$ 312,996	$ 282,984
Basic common shares outstanding													13,978	13,984	12,538
Diluted shares outstanding													14,061	14,057	12,586
Basic net income per share (dollars per share)	$ 14.23	$ 7.43	$ 6.76	$ 13.57	$ 8.10	$ 5.33	$ 2.67	$ 6.28	$ 6.98	$ 4.69	$ 2.24	$ 9.53	$ 41.99	$ 22.38	$ 22.57
Diluted net income per share (dollars per share)	$ 14.14	$ 7.39	$ 6.72	$ 13.49	$ 8.05	$ 5.30	$ 2.66	$ 6.25	$ 6.95	$ 4.67	$ 2.24	$ 9.50	$ 41.74	$ 22.27	$ 22.48
Stock Options [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares													9	11	12
Restricted Stock Units (RSUs) [Member]
Earnings Per Share [Line Items]
Dilutive potential common shares													74	62	36