Shareholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Jan. 31, 2017	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 06, 2017	Aug. 13, 2012
Class of Stock [Line Items]
Dividend payable date			Mar. 31, 2017
Dividend recorded date			Mar. 17, 2017
Issuance of common stock Dividend Reinvestment Plan		100,000,000	100,000,000	100,000,000
Number of stock option granted			105,000	286,000	280,000
Number of performance-based awards outstanding		53,000	53,000	53,000
Share-based compensation expense			$ 2,200,000	$ 1,900,000	$ 1,700,000
Tax benefit related to stock based compensation expense			$ 200,000	0	200,000
Number of shares authorized in employee stock purchase plan		1,500,000	1,500,000
Employee stock purchase plan period			10 years
Discount from market price			15.00%
Employees offering dates intervals			6 months
Employee stock purchase plan expense			$ 71,000	54,000	19,000
Contributions to the employees' stock ownership trust in cash			$ 0	$ 0	$ 0
Contributions to the employees' stock ownership trust in shares			0	0	0
Weighted-average fair value of stock options granted			$ 2.07	$ 4.35	$ 6.48
Expected Volatility Rate			39.00%	44.00%	55.00%
Expected Term Period			6 years 6 months	6 years 3 months 18 days	6 years 3 months 18 days
Risk-Free Interest Rate			2.10%	1.90%	2.20%
Expected dividend rate			3.60%	2.40%	1.70%
Cash received from employee stock option exercised			$ 1,300,000	$ 100,000	$ 1,200,000
Intrinsic value of option exercised			$ 1,000,000	$ 200,000	2,400,000
Warrants issued to acquire Icarus Share		250,000	250,000
Warrants exercise price		$ 9.07	$ 9.07
Warrants expiration date			Dec. 26, 2016
Common stock, shares issued		34,300,209	34,300,209	34,055,749
Aggregate value transaction value of share purchased			$ 1,238,000		$ 973,000
Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares issued		89,640	89,640
Shares issued, price per share		$ 9.07	$ 9.07
Share purchased			105,000	0	61,500
Aggregate value transaction value of share purchased			$ 1,000		$ 1,000
Common Stock [Member] | Former Owner of Subsidiary Acquired [Member]
Class of Stock [Line Items]
Share purchased			30,000
Common Stock [Member] | Current Segment President [Member]
Class of Stock [Line Items]
Share purchased		75,000	75,000
Restricted Stock [Member]
Class of Stock [Line Items]
Unrecognized compensation expense related to stock options and restricted stock		$ 6,500,000	$ 6,500,000
Weighted average vesting period			3 years
Dividend Reinvestment Plan [Member]
Class of Stock [Line Items]
Issuance of common stock Dividend Reinvestment Plan							750,000
2007 Plan [Member]
Class of Stock [Line Items]
Number of stock option granted			105,000	286,000
Number of restricted stock awards granted			267,000	323,000
Number of shares reserved for issuance		3,300,000	3,300,000
Shares available for future grant		414,000	414,000
2007 Plan [Member] | Minimum [Member]
Class of Stock [Line Items]
2007 stock options or stock awards, vesting period			4 years
2007 Plan [Member] | Maximum [Member]
Class of Stock [Line Items]
2007 stock options or stock awards, vesting period			5 years
2007 Plan [Member] | Employee Stock Option [Member] | Minimum [Member]
Class of Stock [Line Items]
2007 stock options or stock awards, vesting period			3 years
2007 Plan [Member] | Employee Stock Option [Member] | Maximum [Member]
Class of Stock [Line Items]
2007 stock options or stock awards, vesting period			5 years
2007 Plan [Member] | Restricted Stock [Member]
Class of Stock [Line Items]
Weighted-average fair value of restricted stock awards granted			$ 9.76	$ 9.48	$ 14.41
Subsequent Event [Member]
Class of Stock [Line Items]
Quarterly dividend declared per share						$ 0.075
Aggregate value transaction value of share purchased	$ 1,100,000