Fair Value of Financial Instruments - Schedule of Debt Instruments Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Gross	$ 55,000
Unsecured Senior Notes | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Senior Notes	0	$ 0
Unsecured Senior Notes | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Senior Notes	0	0
Unsecured Senior Notes | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unsecured Senior Notes	52,700	50,000
Unsecured Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Gross	55,000	55,000
Unsecured Senior Notes | Unsecured Senior Notes | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Gross	55,000	55,000
Wells Fargo Revolving Credit Facility | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Wells Fargo revolving credit facility	0	0
Wells Fargo Revolving Credit Facility | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Wells Fargo revolving credit facility	0	0
Wells Fargo Revolving Credit Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-Term Debt	54,613	37,055
Wells Fargo Revolving Credit Facility | Wells Fargo Revolving Credit Facility | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-Term Debt	$ 54,613	$ 37,055