Shareholders' Equity Additional Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stockholders Equity Note [Line Items]
Common Stock, Dividends, Per Share, Declared	$ 0.48
Repurchase and retirement of common stock			$ 3,945
Repurchase and retirement of common stock, shares	30
Shares remaining available for repurchases	1,574		1,574
Cash dividend paid during period, per share	$ 0.48	$ 0.42	$ 0.96	$ 0.84
Common stock excluded from calculation of diluted earnings per share	665	1,018	513	799