CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net Income	$ 14,640	$ 15,298
Net unrealized holding gains on marketable securities:
Unrealized holding gains net of tax of $(3,579) and $(436), respectively	5,596	670
Reclassification adjustment for gains included in net income, net of tax of $1,218 and $43, respectively	(1,904)	(66)
Net unrealized holding gains on marketable securities	3,692	604
Change in fair value of interest rate swaps, net of tax of $(135) and $(367), respectively	251	680
Defined benefit plan:
Reclassification adjustment for prior period service costs included in net income, net of tax of $75 and $(123), respectively	(138)	229
Other comprehensive income	3,805	1,513
Total comprehensive income	$ 18,445	$ 16,811