Credit Facility (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Credit Facility
Principal payments of Term Loan
Amortization and interest expense capitalized	$ 159	$ 227	$ 585	$ 710
Amortization and interest expense expensed	36	$ 86	144	$ 182
Amortization of debt issuance costs
October 1, 2017 - December 31, 2017			61
January 1, 2018 - December 31, 2018			217
Amortization of debt issuance costs			$ 278
Credit Facility | Minimum
Principal payments of Term Loan
Interest rate percentage			3.50%
Credit Facility | Maximum
Principal payments of Term Loan
Interest rate percentage			3.80%
Credit Facility | LIBOR | Minimum
Credit Facility
Spread on floating interest rate (as a percent)			2.50%
Credit Facility | LIBOR | Maximum
Credit Facility
Spread on floating interest rate (as a percent)			3.50%
Credit Facility | Prime Rate | Minimum
Credit Facility
Spread on floating interest rate (as a percent)			1.50%
Credit Facility | Prime Rate | Maximum
Credit Facility
Spread on floating interest rate (as a percent)			2.50%
Revolving Line of Credit
Credit Facility
Current issued borrowing capacity	69,750		$ 69,750
Line Of Credit Facility Contingent Increase To Maximum Borrowing Capacity	86,500		86,500
Outstanding balance	5,000		$ 5,000		$ 15,000
Revolving Line of Credit | Minimum
Credit Facility
Fee on unused portion of Revolving Line of Credit (as a percent)			0.375%
Revolving Line of Credit | Maximum
Credit Facility
Fee on unused portion of Revolving Line of Credit (as a percent)			0.50%
Term Loan
Credit Facility
Current issued borrowing capacity	3,500		$ 3,500
Outstanding balance	1,094		$ 1,094		$ 1,969
Term of the debt			4 years
Principal payments of Term Loan
October 1, 2017 - December 31, 2017	219		$ 219
January 1, 2018 - December 31, 2018	875		875
Total	$ 1,094		$ 1,094