Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 20,973	$ 19,802
Unrealized gains and losses on securities available for sale:
Net unrealized gains arising during the period	7,094	3,711
Reclassification adjustment for gains included in net income	(57)	(1)
Total	7,037	3,710
Unrealized losses on derivatives	(421)	0
Amortization (accretion) related to post-retirement obligations	99	(4)
Total other comprehensive income	6,715	3,706
Total comprehensive income	$ 27,688	$ 23,508

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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