Statements Of Changes In Shareholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Retained Earnings [Member]	Capital In Excess Of Par Value [Member]
Balance at Dec. 31, 2011	$ 856,519	$ 8,616	$ 713,500	$ 134,403
Balance, in shares at Dec. 31, 2011		86,165,000
Net income	169,452		169,452
Adjustments to Additional Paid in Capital, Other	(2)			(2)
Balance at Dec. 31, 2012	1,025,969	8,616	882,952	134,401
Balance, in shares at Dec. 31, 2012		86,165,000
Net income	206,113		206,113
Balance at Dec. 31, 2013	1,232,082	8,616	1,089,065	134,401
Balance, in shares at Dec. 31, 2013		86,165,000
Net income	267,514		267,514
Stock Repurchased During Period, Shares	(70,620)	(71,000)
Stock Repurchased and Retired During Period, Value	5,532	7	5,525
Balance at Dec. 31, 2014	$ 1,494,064	$ 8,609	$ 1,351,054	$ 134,401
Balance, in shares at Dec. 31, 2014		86,094,000