Consolidated Statement of Comprehensive Income (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net income	$ 21,005	$ 22,382
Other comprehensive income:
Increase in net unrealized gains on securities available for sale	1,384	4,070
Deferred tax expense	(582)	(1,712)
Increase in net unrealized gains on securities available for sale, net of tax	802	2,358
Post-retirement benefit transition obligation amortization	15	15
Deferred tax expense	(6)	(6)
Post-retirement benefit transition obligation amortization, net of tax	9	9
Total other comprehensive income	811	2,367
Total comprehensive income	$ 21,816	$ 24,749