Stockholders' Equity - Changes in Stockholders' Equity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Equity [Abstract]
Beginning Balance			$ 269,950
Net income for the six months ended June 30, 2014	4,291	6,828	9,181	13,753
Cash dividends declared			(5,503)
Amortization of stock based compensation			1,710
Issued, purchased, retired common stock, and other			19
Ending Balance	$ 275,357		$ 275,357