Stockholders' Equity (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Class of Stock [Line Items]
Stock Repurchased	2,100,000
Treasury Stock, Value, Acquired, Cost Method	$ 58,600,000
Shares Paid for Tax Withholding for Share Based Compensation	7,942
2012 Repurchase Program [Member]
Class of Stock [Line Items]
Maximum number of shares authorized to be repurchased	5,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,938,689
Stock Repurchased	0
IGC [Member]
Class of Stock [Line Items]
Stock Repurchased and Retired During Period, Shares		935,231