Stockholders' Equity - Reconciliation of Number of Shares of Common Stock (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Stockholders Equity Note [Abstract]
Common stock, beginning of period	52,169	54,834
Shares issued for stock options exercised	89	4
Shares of common stock issued upon lapse of restricted stock units ("RSUs")	407	381
Common stock retired	(4,094)	(1,537)
Common stock, end of period	48,571	53,682