Notes Payable and Subordinated Borrowings - Additional Information (Details) - USD ($)		1 Months Ended		3 Months Ended
	Mar. 30, 2016	Apr. 30, 2017	Feb. 28, 2017	Mar. 31, 2017	Dec. 31, 2016
Notes Payable [Line Items]
Minimum Repayment of Aggregate Principal Amount of Senior Notes (as a percent)				5.00%
Outstanding Principal Amount of Senior Notes (as a percent)				100.00%
Subordinated Borrowing, Interest Rate				5.50%
Subordinated Borrowings				$ 10,550,000	$ 16,550,000
Subordinated Debt [Member]
Notes Payable [Line Items]
Extinguishment of Debt, Amount			$ 6,000,000
Subordinated Debt [Member] | Subsequent Event [Member]
Notes Payable [Line Items]
Extinguishment of Debt, Amount		$ 3,751,000
Parent Company [Member] | Senior Notes [Member]
Notes Payable [Line Items]
Extinguishment of Debt, Amount	$ 120,000,000
Parent Company [Member] | Senior Notes [Member]
Notes Payable [Line Items]
Long-term Debt, Gross	170,000,000
Parent Company [Member] | Series A Senior Notes [Member]
Notes Payable [Line Items]
Long-term Debt, Gross	$ 38,000,000
Debt Instrument, Interest Rate, Stated Percentage	4.88%
Parent Company [Member] | Series B Senior Notes [Member]
Notes Payable [Line Items]
Long-term Debt, Gross	$ 67,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.23%
Parent Company [Member] | Series C Senior Notes [Member]
Notes Payable [Line Items]
Long-term Debt, Gross	$ 48,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.48%
Parent Company [Member] | Series D Senior Notes [Member]
Notes Payable [Line Items]
Long-term Debt, Gross	$ 17,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.58%