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Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) - USD ($) $ in Thousands | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2018 | Dec. 31, 2017
Goodwill and Intangible Assets [Roll Forward] |  |  |  |
Total goodwill, beginning of period | $ 765,842 |  |  |
Total goodwill, end of period | 765,842 | $ 765,842 |  |
CDI current period amortization | (2,748) | (3,188) |  |
Indefinite-lived Intangible Assets (Excluding Goodwill) | 919 | 919 |  |
Other intangible assets, net | 43,189 | 54,985 | $ 45,937 |
Total goodwill and intangible assets, end of period | $ 809,031 | 820,827 |  |
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
Accumulated amortization at beginning of period |  |  | $ (60,455) | $ (48,219)
Core deposit intangible, net, beginning of period | $ 45,018 | 57,254 |  |
CDI current period amortization | (2,748) | (3,188) |  |
Total core deposit intangible, end of period | $ 42,270 | $ 54,066 |  |

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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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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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 + Details
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