Adjustments To Previously Reported Amounts (Schedule Of Error Corrections And Prior Period Adjustments) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Prepaid expenses and other assets	$ 37,313		$ 37,313		$ 29,018
Income taxes payable	4,152		4,152		5,450
Retained earnings	673,040		673,040		644,085
Other expense	(1,121)	$ (1,359)	(1,582)	$ (1,517)
Income tax expense	4,213	3,691	13,046	12,346
Net income	$ 20,565	$ 16,906	$ 55,980	$ 57,903
Basic earnings per share	$ 0.4	$ 0.32	$ 1.08	$ 1.08
Diluted earnings per share	$ 0.4	$ 0.31	$ 1.07	$ 1.06
Net cash provided by operations			$ 118,722	$ 113,368
Effect of exchange rate changes			$ (1,041)	(911)
As Previously Reported [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Prepaid expenses and other assets					30,453
Income taxes payable					5,470
Retained earnings					645,500
Other expense		$ (1,105)		(980)
Income tax expense		3,695		12,355
Net income		$ 17,156		$ 58,431
Basic earnings per share		$ 0.32		$ 1.09
Diluted earnings per share		$ 0.32		$ 1.07
Net cash provided by operations				$ 113,905
Effect of exchange rate changes				(1,448)
As Revised [Member}
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Prepaid expenses and other assets					29,018
Income taxes payable					5,450
Retained earnings					$ 644,085
Other expense		$ (1,359)		(1,517)
Income tax expense		3,691		12,346
Net income		$ 16,906		$ 57,903
Basic earnings per share		$ 0.32		$ 1.08
Diluted earnings per share		$ 0.31		$ 1.06
Net cash provided by operations				$ 113,368
Effect of exchange rate changes				$ (911)