Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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The estimated value of gains (losses), net anticipated to be transferred in the future from accumulated other comprehensive income into earnings.

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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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Fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as an asset.

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Net Increase or Decrease in the fair value of the embedded derivative or group of embedded derivatives included in earnings in the period.

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Fair value as of the balance sheet date of all interest rate derivative assets designated as cash flow hedging instruments.

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The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer.

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Derivatives and Hedging Activities - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017 USD ($) Contract $ / shares shares	Dec. 31, 2016 USD ($) shares	Dec. 01, 2016 USD ($)
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	$ 18,190,000		$ 10,800,000
Business Acquisitions, Purchase Price Allocation, Subsequent Years, Remaining Adjustments	$ 1,600,000
Preferred Stock, Shares Issued \| shares	867,846
Preferred Stock, Redemption Price Per Share \| $ / shares	$ 50.00
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net	$ 5,800,000
Credit Default Option [Member]
Derivative [Line Items]
Credit Risk Related Contingent Features Termination Value	2,800,000
Net Liability Position [Member]
Derivative [Line Items]
Credit Risk Related Contingent Features Termination Value	2,800,000
ERROR in label resolution.
Derivative [Line Items]
Fair Value of Credit Risk Derivatives	$ 2,600,000
Designated as Hedging Instrument [Member] \| Interest Rate Caps
Derivative [Line Items]
Derivative, Number of Instruments Held \| Contract	2
Derivative, Notional Amount	$ 50,000,000
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Number of Instruments Held \| Contract	10
Derivative, Notional Amount	$ 550,000,000
Designated as Hedging Instrument [Member] \| Interest Expense
Derivative [Line Items]
Change in fair value of interest rate derivatives included in AOCI and expected to be reclassified in the next 12 months	(80,500)
Other Assets [Member]
Derivative [Line Items]
Interest Rate Cash Flow Hedge Asset at Fair Value	2,000,000	$ 2,400,000
Interest Rate Swap [Member]
Derivative [Line Items]
Fair market value of interest rate swaps	7,600,000	$ 2,600,000
Changes Measurement [Member]
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	$ 7,400,000
Parent Company [Member]
Derivative [Line Items]
Preferred Stock, Shares Issued \| shares	867,846	867,846
Interest Rate Cash Flow Hedge Asset at Fair Value	$ 2,000,000	$ 2,400,000
Fair market value of interest rate swaps	$ 2,602,000	$ 7,562,000