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Employee Benefit Plans (Schedule of Long-term Rate of Return on Assets (Details) | 12 Months Ended
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Dec. 31, 2016
Fixed Income [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Percent of Total Portfolio | 48.00%
One-Year Nominal Return | 4.51%
Annual Standard Deviation | 4.64%
Large Cap U.S. Equities [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Percent of Total Portfolio | 10.00%
One-Year Nominal Return | 7.36%
Annual Standard Deviation | 16.14%
U.S. Large Cap Growth [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Percent of Total Portfolio | 18.00%
One-Year Nominal Return | 7.67%
Annual Standard Deviation | 17.31%
Small Cap U.S. Equities [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Percent of Total Portfolio | 8.00%
One-Year Nominal Return | 8.49%
Annual Standard Deviation | 20.02%
International (Developed) [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Percent of Total Portfolio | 15.00%
One-Year Nominal Return | 8.89%
Annual Standard Deviation | 19.35%
International (Emerging) [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Percent of Total Portfolio | 1.00%
One-Year Nominal Return | 10.68%
Annual Standard Deviation | 27.66%

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- Definition The expected percentage of annual standard deviation on assets. + References No definition available. + Details
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Namespace Prefix: | cass_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition The expected percentage of one-year nominal return on assets. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

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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. + References No definition available. + Details
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- Definition Target allocation of investments of this type to total plan assets presented on a weighted average basis. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(i) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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- Details
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- Details
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- Details
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- Details
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- Details
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- Details
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