Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 0	$ 57,500	$ 0
Finite-lived Intangible Assets [Roll Forward]
CDI and CRI Balance, beginning of period	119,497	61,997	64,187
Accumulated Amortization, beginning of period	(39,871)	(34,809)	(27,821)
Amortization	(6,346)	(5,062)	(3,064)
CDI and CRI Balance, end of period	119,497	119,497	64,187
Accumulated Amortization, end of period	(46,217)	(39,871)	(30,885)
Net CDI and CRI, end of period	$ 73,280	$ 79,626	$ 33,302

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

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No definition available.

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