Stockholders' Equity - Common Stock Purchased Including Purchase of Common Stock for Tax Withholdings (Details) - USD ($)		3 Months Ended												12 Months Ended			36 Months Ended
	Mar. 06, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased (shares)		16,719	13,884	65,791	291,861	189,438	502,942	177,330	247,797	263,772	0	0	0	388,255	1,117,507	263,772	1,769,534
Average Price Paid Per Share (usd per share)		$ 16.43	$ 16.46	$ 16.38	$ 16.76	$ 16.87	$ 16.52	$ 16.93	$ 17.31	$ 16.36	$ 0.00	$ 0.00	$ 0.00	$ 16.67	$ 16.82	$ 16.36	$ 16.72
Commissions														$ 15,410
Stock repurchased during period (shares)														388,255
Publicly Announced Plans or Programs
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Purchased (shares)		16,719	13,884	65,791	291,861	189,438	502,942	177,330	27,467	263,772	0	0	0	388,255	897,177	263,772	1,549,204
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Publicly Announced Plans or Programs		$ 3,525,000	$ 3,800,000	$ 4,028,000	$ 5,106,000	$ 0	$ 3,224,000	$ 11,531,000	$ 14,536,000	$ 10,685,000	$ 15,000,000	$ 15,000,000	$ 15,000,000
2012 STIP and 2009 LTIP
Equity, Class of Treasury Stock [Line Items]
Stock repurchased during period (shares)	220,330
Common stock repurchase price (usd per share)	$ 17.36