Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies - Short-Term Investments (Details)

Summary of significant accounting policies - Short-Term Investments (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Oct. 26, 2011
Guarantor Obligations [Line Items]
Short-Term Investments, Minimum Maturity Term	3 months
Short-Term Investments, Maximum Maturity Term	1 year
Financial guarantee
Guarantor Obligations [Line Items]
Letter of credit outstanding		$ 180,000
Certificate of deposit securing letter of credit		180,000
Promissory note receivable amount		$ 180,000
Promissory note receivable, stated interest rate		6.00%

- Definition

A savings certificate entitling the Entity (that is, bearer) to receive interest at an established maturity date, based upon a fixed interest rate. A certificate of deposit may be issued in any denomination. Certificates of deposit are generally issued by commercial banks and, therefore, insured by the FDIC (up to the prescribed limit). Certificates of deposit generally restrict holders from withdrawing funds on demand without the incurrence of penalties. Generally, only certificates of deposit with original maturities of three months or less qualify as cash equivalents. Original maturity means original maturity to the entity holding the investment. As a related example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

+ References + Details