Goodwill and Other Intangible Assets Summary of Core Deposit and Other Intangibles (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Summary of core deposit intangibles and other intangibles
Amortization of other intangible assets	$ 801us-gaap_AmortizationOfIntangibleAssets	$ 991us-gaap_AmortizationOfIntangibleAssets
Core Deposit Intangibles [Member]
Summary of core deposit intangibles and other intangibles
Gross carrying amount	36,230		36,230
Accumulated amortization	(34,875)		(34,433)
Amortization Expense	1,355		1,797
Amortization of other intangible assets	442		2,868
Other Intangibles [Member]
Summary of core deposit intangibles and other intangibles
Gross carrying amount	30,898		19,283
Accumulated amortization	(14,002)		(13,643)
Amortization Expense	16,896		5,640
Additions during the period	11,615		0
Amortization of other intangible assets	$ 359		$ 879

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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