Common Stock - Stock Repurchase Program (Details) - USD ($)	3 Months Ended		9 Months Ended		25 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Jun. 30, 2015	Nov. 30, 2012
Equity, Class of Treasury Stock [Line Items]
Cost of repurchase of common stock			$ 4,174,000
Stock repurchase program, remaining amount	$ 50,700,000		50,700,000
Credit Facility
Equity, Class of Treasury Stock [Line Items]
Share repurchase covenant			$ 10,700,000
Share Repurchase Program, November 2012
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount (up to)							$ 25,000,000
Repurchase of common stock during period (in shares)	630,000	0	680,000	0
Cost of repurchase of common stock	$ 3,700,000		$ 4,200,000
Average common stock repurchase price (in dollars per share)	$ 5.85		$ 6.14
Share Repurchase Program, June 2015
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount (up to)						$ 50,000,000
Repurchase of common stock during period (in shares)					0