Bank Loans	6 Months Ended
Jun. 30, 2015
Bank Loans [Abstract]
Bank Loans	5. Bank loans The Company has a line of credit (the “Credit Facility”) with Wells Fargo Bank, National Association (“Wells Fargo”). The Credit Facility has a borrowing limit of $250.0 million and expires May 1, 2019. The rate of interest charged on borrowings is based on the London Interbank Offered Rate (“LIBOR”) plus 0.875% to LIBOR plus 1.70% depending on the Company’s credit ratings. Currently, the Company’s rate under the Credit Facility is LIBOR plus 0.925%. In addition, the Company is required to pay an annual facility fee ranging from 0.125% to 0.30% of the borrowing limit depending on the Company’s credit ratings (currently 0.15%). The Company had no balance outstanding on the Credit Facility at June 30, 2015 and December 31, 2014. The Company had $885,000 and $1.0 million of unamortized commitment fees as of June 30, 2015 and December 31, 2014, respectively. The Credit Facility requires the Company to meet certain covenants, all of which the Company was in compliance with as of June 30, 2015. Interest on outstanding borrowings is payable monthly.

5. Bank loans

The Company has a line of credit (the “Credit Facility”) with Wells Fargo Bank, National Association (“Wells Fargo”). The Credit Facility has a borrowing limit of $250.0 million and expires May 1, 2019. The rate of interest charged on borrowings is based on the London Interbank Offered Rate (“LIBOR”) plus 0.875% to LIBOR plus 1.70% depending on the Company’s credit ratings. Currently, the Company’s rate under the Credit Facility is LIBOR plus 0.925%. In addition, the Company is required to pay an annual facility fee ranging from 0.125% to 0.30% of the borrowing limit depending on the Company’s credit ratings (currently 0.15%). The Company had no balance outstanding on the Credit Facility at June 30, 2015 and December 31, 2014. The Company had $885,000 and $1.0 million of unamortized commitment fees as of June 30, 2015 and December 31, 2014, respectively. The Credit Facility requires the Company to meet certain covenants, all of which the Company was in compliance with as of June 30, 2015. Interest on outstanding borrowings is payable monthly.