Subsequent Event

3 Months Ended

Mar. 31, 2018

Subsequent Events [Abstract]

Subsequent Event

13.  Subsequent Event

In April 2018, we entered into an accelerated share repurchase program (ASR) with a financial institution to repurchase $500 million of our common stock as part of our $1.5 billion share repurchase program.  Under the terms of the ASR, we paid $500 million in cash to the financial institution and received an initial delivery of approximately 8 million shares of our common stock with final settlement expected to be completed during the second quarter.