Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net income applicable to common stock	$ 6,583	$ 7,487
Average number of common shares outstanding	26,861,565	26,842,047
Less: Average unallocated ESOP shares	(1,964,339)	(2,040,249)
Less: Average unvested restricted stock awards	(724,989)	(890,379)
Average number of common shares outstanding used to calculate basic earnings per common share	24,172,237	23,911,419
Average number of common shares outstanding used to calculate diluted earnings per common share	24,827,850	24,275,665
Earnings per common share:
Basic (dollars per share)	$ 0.27	$ 0.31
Diluted (dollars per share)	$ 0.27	$ 0.31
Antidilutive securities excluded from computation of earnings per share (shares)	552,950	362,100
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Effect of dilutive share-based compensation awards (in shares)	432,287	139,392
Unvested Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Effect of dilutive share-based compensation awards (in shares)	223,326	224,854

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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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.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of employee stock ownership plan (ESOP) shares that have not been committed to be released determined by relating the portion of time within a reporting period that these shares have been outstanding to the total time in that period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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Number of shares of restricted stock determined by relating the portion of time within a reporting period that restricted shares have been outstanding to the total time in that period. Restricted shares are subject to sales, contractual, regulatory or other restrictions that prevent or inhibit the holder from freely disposing of them before the restriction ends.

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