XML 23 R9.htm IDEA: XBRL DOCUMENT v3.10.0.1
CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Convertible Senior Notes 0.375 Percent Due 2018      
Interest rate of debt (as a percent) 0.375% 0.375% 0.375%
Convertible Senior Notes 1.25 Percent Due 2020      
Interest rate of debt (as a percent) 1.25% 1.25% 1.25%