CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - shares	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Issuance of shares of Common Stock upon exercise of stock options and restricted stock units	400,292	1,044,745	369,109	623,709
Issuance of shares of Common Stock under the ESPP	143,379		150,538
Issuance of shares of Common Stock for services rendered	1,444	1,200	1,281	1,032
Convertible Senior Notes 0.375 Percent Due 2018
Issuance of shares of Common Stock upon conversion of convertible senior notes			38	539