Fair Value Measurement - Quantitative Information About Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Nonrecurring Basis (Detail) - Fair Value, Measurements, Nonrecurring [Member] $ in Thousands	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 247	$ 247
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)	ucfc:ValuationTechniqueSalesComparisonApproachMember	ucfc:ValuationTechniqueSalesComparisonApproachMember
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0000	0.0000
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.3500	0.3500
Impaired Loans [Member] | Multifamily [Member] | Commercial Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.1500	0.1500
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value		$ 2
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)		ucfc:ValuationTechniqueSalesComparisonApproachMember
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.0000
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.3500
Impaired Loans [Member] | Nonresidential [Member] | Commercial Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.1500
Impaired Loans [Member] | Auto [Member] | Consumer Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 16
Impaired Loans [Member] | Auto [Member] | Consumer Loans [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)	ucfc:ValuationTechniqueSalesComparisonApproachMember
Impaired Loans [Member] | Auto [Member] | Consumer Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0000
Impaired Loans [Member] | Auto [Member] | Consumer Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.1785
Impaired Loans [Member] | Auto [Member] | Consumer Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0893
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 38
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)	ucfc:ValuationTechniqueSalesComparisonApproachMember
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0000
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.1785
Impaired Loans [Member] | Marine [Member] | Consumer Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0893
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value		$ 40
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)		ucfc:ValuationTechniqueSalesComparisonApproachMember
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.0000
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.6400
Impaired Loans [Member] | Secured [Member] | Commercial Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.1600
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value		$ 89
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)		ucfc:ValuationTechniqueSalesComparisonApproachMember
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.0000
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.1785
Impaired Loans [Member] | Home Equity [Member] | Consumer Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales		0.0893
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 130	$ 1,010
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)	ucfc:ValuationTechniqueSalesComparisonApproachMember	ucfc:ValuationTechniqueSalesComparisonApproachMember
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0000	0.0000
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.1077	0.1077
Impaired Loans [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0427	0.0427
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 197	$ 354
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)	ucfc:ValuationTechniqueSalesComparisonApproachMember	ucfc:ValuationTechniqueSalesComparisonApproachMember
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0000	0.0000
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.6000	0.5290
Other Real Estate Owned [Member] | Construction [Member] | Commercial Loans [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.5767	0.5241
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 145	$ 82
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Valuation Technique(s)	ucfc:ValuationTechniqueSalesComparisonApproachMember	ucfc:ValuationTechniqueSalesComparisonApproachMember
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Minimum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.0000	0.0000
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Maximum [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.2215	0.1343
Other Real Estate Owned [Member] | Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Weighted Average [Member] | Sales Comparison Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Adjustment for differences between comparable sales	0.1636	0.1343