CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net income	$ 175,459	$ 156,959	$ 105,505
Other comprehensive income:
Net unrealized appreciation (depreciation) of investment securities during the year, net of income taxes of $(2,120), $2,028 and $2,950, respectively	(3,635)	3,493	4,974
Valuation allowance on investment securities' deferred tax asset during the year	(2,955)	963
Pension and postretirement benefits, net of income taxes of $(13,232), $628 and $(821), respectively	(22,062)	1,061	(949)
Reclassification adjustments for amounts included in net income, net of income taxes of $(830), $(1,139) and $159, respectively	(1,428)	(1,980)	264
Comprehensive income	$ 145,379	$ 160,496	$ 109,794