Benefit Plans - Additional Information (Detail) - USD ($)		12 Months Ended
	Jan. 29, 2014	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		$ 628,000
Salary expense		10,800,000	$ 10,500,000	$ 9,000,000
Expense for contributions to savings and investment plan		$ 7,100,000	6,700,000	$ 7,100,000
Maximum annual contributions based on employee's salary		5.00%		6.00%
Maximum annual contributions per employee		$ 13,500
Shares of common stock were available for issuance (in shares)		7,300,000
Stock-based compensation expense		$ 12,204,000	10,032,000	$ 7,575,000
Unrecognized stock-based compensation		$ 11,600,000
Average remaining vesting, years		2 years
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		$ 12,200,000	10,000,000	8,800,000
Stock awards granted		$ 4,300,000	$ 3,500,000	$ 2,600,000
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)		$ 11.05	$ 8.32	$ 8.98
Restricted Stock
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Granted (in shares)		608,786	544,307	886,427
Vested (in shares)		736,575	1,050,293	559,958
Performance Based Restricted Stock
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Granted (in shares)					240,000
Vested (in shares)		85,000	53,000	50,000
Performance Shares
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Award vesting period		3 years
Granted (in shares)		371,000	431,000	313,000
Compensation costs related to restricted stock awards		$ 3,800,000	$ 2,800,000	$ 2,300,000
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)		$ 11.70
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		1 year
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		3 years
Funded plans for former directors
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Projected benefit obligation		$ 682,000	$ 1,100,000
Non-employee directors | RSUs
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Granted (in shares)		45,000
Grant date fair value of awards		$ 50,000
Equity securities
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Cumulative annual real return		7.00%
Equity securities | Minimum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Target asset allocation percentage		25.00%
Equity securities | Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Target asset allocation percentage		65.00%
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 | Minimum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Target asset allocation percentage		35.00%
Debt securities | Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Target asset allocation percentage		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		3.69%	4.12%
Nonqualified Plan | Other Pension Plan, Defined Benefit | Non-qualified plans for former directors
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Projected benefit obligation		$ 2,100,000	$ 2,700,000
Nonqualified Plan | Other Pension Plan, Defined Benefit | Funded plans for former directors
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Obligation included in other comprehensive loss, net of tax		818,000	951,000
Obligation included in other comprehensive loss, tax		$ 577,000	$ 674,000