Earnings Per Share - Schedule of Basic Earnings Per Common Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distributed earnings	$ 9,896	$ 9,842
Undistributed earnings (distributed capital)	(9,193)	9,177
Total earnings to common shareholders	703	19,019
Distributed earnings	$ 0.34	$ 0.34
Undistributed earnings (distributed capital)	$ (0.32)	$ 0.32
Total earnings per common share - Basic	$ 0.02	$ 0.66
Unvested restricted stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distributed earnings	199	194
Undistributed earnings (distributed capital)	(185)	180
Total earnings allocated to restricted stock	$ 14	$ 374
Distributed earnings	$ 0.35	$ 0.36
Undistributed earnings (distributed capital)	$ (0.33)	$ 0.34
Total earnings per common share - Basic	$ 0.03	$ 0.70

The total amount of dividends declared in the period for each class of stock and the contractual amount of dividends (or interest on participating income bonds) that must be paid for the period (for example, unpaid cumulative dividends). Dividends declared in the current period do not include dividends declared in respect of prior-period unpaid cumulative dividends. Preferred dividends that are cumulative only if earned are deducted only to the extent that they are earned.

+ References+ Details

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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+ Details