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Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | Mar. 31, 2018 | Dec. 31, 2017 | Mar. 31, 2017 | Dec. 31, 2016
Goodwill and Intangible Assets [Roll Forward] |  |  |  |  |  |  |  |  |  |
Total goodwill, beginning of period |  |  |  | $ 765,842 |  |  |  |  |  |
Total goodwill, end of period | $ 765,842 | [1] | $ 382,762 | 765,842 | [1] | $ 382,762 |  |  |  |
CDI current period amortization | (3,088) |  | (1,249) | (6,276) |  | (2,598) |  |  |  |
Indefinite-lived Intangible Assets (Excluding Goodwill) | 919 |  | 919 | 919 |  | 919 |  |  |  |
Other intangible assets, net | 51,897 |  | 15,033 | 51,897 |  | 15,033 |  | $ 58,173 |  |
Total goodwill and intangible assets, end of period | 817,739 |  | 397,795 | $ 817,739 |  | 397,795 |  |  |  |
Core Deposits [Member] |  |  |  |  |  |  |  |  |  |
Goodwill and Intangible Assets [Line Items] |  |  |  |  |  |  |  |  |  |
Estimated life of CDI, in years |  |  |  | 10 years |  |  |  |  |  |
Goodwill and Intangible Assets [Roll Forward] |  |  |  |  |  |  |  |  |  |
Gross core deposit intangible balance, beginning of period |  |  |  |  |  |  | $ 105,473 | 105,473 | $ 58,598 | $ 58,598
Accumulated amortization at beginning of period |  |  |  |  |  |  | $ (51,407) | $ (48,219) | $ (43,235) | $ (41,886)
Core deposit intangible, net, beginning of period | 54,066 |  | 15,363 | $ 57,254 |  | 16,712 |  |  |  |
CDI current period amortization | (3,088) |  | (1,249) | (6,276) |  | (2,598) |  |  |  |
Total core deposit intangible, end of period | $ 50,978 |  | $ 14,114 | $ 50,978 |  | $ 14,114 |  |  |  |
[1] | See Note 3, “Business Combinations,” for additional information regarding goodwill and intangible assets recorded related to the acquisition of Pacific Continental on November 1, 2017.

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- Definition 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. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -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 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -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 + Details
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