Stockholders' Equity - Reconciliation of Denominators used in Computation of Basic and Diluted Earnings Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Basic weighted average shares outstanding (in shares)	287,642,801	289,242,447
Weighted shares assumed upon exercise of stock options (in shares)	232,962	213,494
Diluted weighted average shares outstanding (in shares)	287,875,763	289,455,941