Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Capital In Excess of Par Value	Accumulated Other Comprehensive Income	Retained Earnings
Beginning balances at Dec. 31, 2009
Comprehensive income (loss):
Net income	$ 146,484	$ 0	$ 0	$ 0	$ 146,484
Other comprehensive income (loss), net of tax	(11,309)	0	0	(11,309)	0
Total comprehensive income	135,175
Activity in employee compensation plans	9,632	88	9,544	0	0
Ending balances at Dec. 31, 2010	1,710,617	9,493	393,501	(6,851)	1,314,474
Comprehensive income (loss):
Net income	195,867	0	0	0	195,867
Other comprehensive income (loss), net of tax	25,877	0	0	25,877	0
Total comprehensive income	221,744
Activity in employee compensation plans	14,656	48	14,608	0	0
Ending balances at Dec. 31, 2011	1,947,017	9,541	408,109	19,026	1,510,341
Comprehensive income (loss):
Net income	23,176	0	0	0	23,176
Other comprehensive income (loss), net of tax	(11,439)	0	0	(11,439)	0
Total comprehensive income	11,737
Activity in employee compensation plans	15,547	53	15,494	0	0
Ending balances at Dec. 31, 2012	$ 1,974,301	$ 9,594	$ 423,603	$ 7,587	$ 1,533,517