CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - shares	3 Months Ended	9 Months Ended		178 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019
Statement of Stockholders' Equity [Abstract]
Repurchase of common stock (in shares)	1,204,300	1,228,102	2,346,427	45,357,495