Consolidated Condensed Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Statement of Other Comprehensive Income [Abstract]
Net income	$ 20,710	$ 31,475
Other comprehensive income, net of tax:
Change in funded status of pension plan, net of income taxes of $222 for the three months ended March 31, 2012		412
Unrealized net holding gain on cash flow hedge, net of income taxes of $60 for the three months ended March 31, 2012		113
Unrealized net holding loss on securities available-for-sale, net of income taxes of $(1,282) and $(1,188) for the three months ended March 31, 2013 and 2012, respectively	(2,379)	(2,202)
Other comprehensive income (loss)	(2,379)	(1,677)
Comprehensive income	$ 18,331	$ 29,798