Long-Term Debt - Credit Facility (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Amount outstanding	$ 34,300,000	$ 38,300,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, extension term	1 year
Line of credit facility, maximum borrowing capacity	$ 75,000,000
Line of credit facility, maximum borrowing capacity, after possible increase	125,000,000
Line of credit facility, current borrowing capacity	$ 40,700,000
Line of credit facility unused portion of the borrowing capacity fee percentage condition	50.00%
Amount outstanding	$ 34,300,000
Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Line of credit facility, basis points added to LIBOR interest rate	1.35%
Line of credit facility, commitment fee percentage on unused portion of the borrowing capacity	0.20%
Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, basis points added to LIBOR interest rate	2.25%
Line of credit facility, commitment fee percentage on unused portion of the borrowing capacity	0.25%
New Repurchase Program [Member]
Debt Instrument [Line Items]
Repurchase of common stock, authorized amount	$ 10,000,000	$ 10,000,000