Benefit Plans - Additional Information (Detail) - USD ($)		2 Months Ended	12 Months Ended
	Jan. 29, 2014	Feb. 24, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Net actuarial loss expected to be recognized as a component of net periodic pension expense				$ 367,000
Discount rate used to compute the obligation				4.33%	4.02%	4.89%
Net periodic pension income				$ (7,564,000)	$ (6,344,000)	$ (5,844,000)
Projected benefit obligation				161,306,000	157,661,000
Salary expense				10,500,000	9,000,000	6,800,000
Expense for contributions to savings and investment plan				$ 6,700,000	$ 7,100,000	$ 6,000,000
Maximum annual contributions based on employee's salary				5.00%	6.00%	6.00%
Maximum annual contributions per employee				$ 13,250
Shares of common stock were available for issuance				8,300,000
Stock-based compensation expense				$ 10,032,000	$ 7,575,000	$ 7,489,000
Unrecognized stock-based compensation				$ 13,800,000
Average remaining vesting, years				2 years 6 months
2016 Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Shares of common stock were available for issuance					2,200,000
2009 Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Shares of common stock were available for issuance					0
Director Restricted Stock Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Additional fees	$ 0
Stock Options and Restricted Stock
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Stock-based compensation expense				$ 10,000,000	$ 8,800,000	7,500,000
Stock awards granted				$ 3,500,000	$ 2,600,000	$ 3,900,000
Stock Options and Restricted Stock | Employee Stock Incentive Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Weighted average grant date fair value (usd per share)				$ 8.32	$ 8.98
Restricted Stock
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Granted (in shares)				544,307	886,427	1,488,960
Vested (in shares)				1,050,293	559,958	524,663
Performance Based Restricted Stock
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Award vesting period				3 years
Granted (in shares)					240,000
Vested (in shares)				53,000	50,000
Performance Based Restricted Stock | Subsequent Event
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Vested (in shares)		85,000
Performance Shares
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Award vesting period				3 years
Compensation costs related to restricted stock awards				$ 2,800,000	$ 2,300,000
Granted (in shares)				431,069	313,212
Performance Shares | Employee Stock Incentive Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Weighted average grant date fair value (usd per share)				$ 8.84
Performance Shares | Vesting based on growth in tangible book value per share plus dividends | Employee Stock Incentive Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Annual vesting percentage				75.00%
Performance Shares | Vesting based on total shareholder return as compared to our peer group | Employee Stock Incentive Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Annual vesting percentage				25.00%
Employer Matching Contribution, Percentage Match One
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan employee matching percentage				100.00%
Maximum annual contributions based on employee's salary				4.00%
Employer Matching Contribution, Percentage Match Two
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan employee matching percentage				50.00%
Maximum annual contributions based on employee's salary				2.00%
Minimum | Restricted Stock
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Award vesting period				3 years
Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Award vesting period				10 years
Maximum | Restricted Stock
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Award vesting period				6 years
Non-qualified plans for former directors
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Projected benefit obligation				$ 3,300,000	$ 3,400,000
Funded plans for former directors
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Projected benefit obligation				1,500,000	1,600,000
Obligation included in other comprehensive loss, net of tax				867,000	1,000,000
Obligation included in other comprehensive loss, tax				614,000	$ 748,000
Non-employee directors | RSUs
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Grant date fair value of awards				$ 50,000
Equity securities
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Target asset allocation for qualified plan, minimum				25.00%
Target asset allocation for qualified plan, maximum				65.00%
Cumulative annual real return				7.00%
Equity securities | Consumer Price Index
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Cumulative annual real return, period				5 years
Equity securities | S&P 500 Index
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Cumulative annual real return, period				3 years
Debt securities
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Target asset allocation for qualified plan, minimum				35.00%
Target asset allocation for qualified plan, maximum				75.00%
Fixed income securities
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Cumulative annual real return				3.00%
Fixed income securities | Consumer Price Index
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Cumulative annual real return, period				5 years
Fixed income securities | Merrill Lynch Intermediate Government/Corporate Index
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Cumulative annual real return, period				3 years
Other Pension Plan, Defined Benefit
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Discount rate used to compute the obligation				4.11%	4.33%
Forecast | Change in Accounting Estimate
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Net periodic pension income			$ 765,000