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.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Goodwill and Identifiable Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Apr. 07, 2017
Goodwill [Line Items]
Impairment charge	$ 338,000	$ 750,000	$ 0
Goodwill	379,627,000	366,156,000	366,156,000
Amortization expense of identifiable intangible assets	6,200,000	6,900,000	7,800,000
Impairment losses on identifiable intangible assets	0	0	0
Future amortization expense for identifiable intangible assets [Abstract]
2018	5,200,000
2019	4,000,000
2020	2,700,000
2021	1,900,000
2022	1,100,000
Reliance [Member]
Goodwill [Line Items]
Goodwill	13,500,000			$ 13,471,000
General Banking And Insurance [Member]
Goodwill [Line Items]
Impairment charge	$ 0	$ 0	$ 0