Loans Receivable - Textuals (Details)	12 Months Ended
	Dec. 31, 2018 segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan segments	4
Maximum percentage consumer loans (percent)	80.00%
One-to-four family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum percent of appraised value or underlying collateral mortgage (not to exceed 80%) residential loans (percent)	80.00%
One-to-four family residential | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan term	15 years
One-to-four family residential | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan term	30 years