Stockholders' Equity - (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Feb. 27, 2018	Oct. 31, 2017	Oct. 31, 2016	Dec. 31, 2014
Class of Stock [Line Items]
Authorized amount for share repurchase program	$ 40,000,000.0				$ 40,000,000	$ 40,000,000
Stock awards outstanding (in shares)		1,501,021
Options outstanding (in shares)	126,680	170,253	288,383				503,134
Stock Options
Class of Stock [Line Items]
Shares repurchased during the period (in shares)		61,980	163,500
Shares repurchased during the period		$ 1,500,000	$ 900,000
Stock repurchased during period, net cash value		$ 1,200,000	$ 3,000,000
Restricted Stock and Restricted Stock Units
Class of Stock [Line Items]
Stock awards outstanding (in shares)	1,428,878	1,501,021	1,275,707				767,540
2016 Employee Plan
Class of Stock [Line Items]
Number of shares authorized for grant (in shares)	2,132,739
2016 Employee Plan | Stock Options
Class of Stock [Line Items]
Stock awards outstanding (in shares)	0
2016 Employee Plan | Restricted Stock and Restricted Stock Units
Class of Stock [Line Items]
Stock awards outstanding (in shares)	448,225
2013 Employee Plan | Stock Options
Class of Stock [Line Items]
Stock awards outstanding (in shares)	0
2013 Employee Plan | Restricted Stock and Restricted Stock Units
Class of Stock [Line Items]
Stock awards outstanding (in shares)	980,653
2009 Employee Plan
Class of Stock [Line Items]
Options outstanding (in shares)	126,680
2009 Employee Plan | Restricted Stock and Restricted Stock Units
Class of Stock [Line Items]
Stock awards outstanding (in shares)	0
2016 Director Plan
Class of Stock [Line Items]
Number of shares authorized for grant (in shares)	166,456
2016 Director Plan | Deferred Stock Units
Class of Stock [Line Items]
Stock awards outstanding (in shares)	49,195
2011 Director Plan | Deferred Stock Units
Class of Stock [Line Items]
Stock awards outstanding (in shares)	119,366
2006 Director Plan | Deferred Stock Units
Class of Stock [Line Items]
Stock awards outstanding (in shares)	46,841
2001 Director Plan | Deferred Stock Units
Class of Stock [Line Items]
Stock awards outstanding (in shares)	54,575
Through The Open Market Repurchase Program
Class of Stock [Line Items]
Shares repurchased during the period (in shares)	1,599,093	2,226,875	1,306,199
Shares repurchased during the period	$ 35,300,000	$ 41,800,000	$ 24,300,000
Average cost per share (in Dollars per share)	$ 22.10	$ 18.76	$ 18.58
In Connection with Equity Compensation Programs
Class of Stock [Line Items]
Authorized amount for share repurchase program	$ 10,000,000
Shares repurchased during the period (in shares)	112,899	61,039	32,902
Shares repurchased during the period	$ 2,500,000	$ 1,200,000	$ 600,000
Average cost per share (in Dollars per share)	$ 22.15	$ 19.65	$ 17.05
Subsequent Event
Class of Stock [Line Items]
Authorized amount for share repurchase program				$ 30,000,000.0