Three Months Ended September 30, 

Nine Months Ended September 30, 

2018

2017

2018

2017

Number of shares repurchased

142,780

1,507,443

156,437

2,365,836

Share repurchase cost (in thousands)

$

9,493

$

100,000

$

(a)

$

139,286

Average price per share

$

66.49

$

66.34

$

(a)

$

58.87

(a)

On May 5, 2017, under the 2017 Repurchase Program, we entered into the 2017 ASR Agreement.  When the agreement became effective on July 5, 2017, we paid BofA $100.0 million in exchange for an initial delivery of 1.5 million shares of our common stock, representing an estimated 80 percent of the total number of shares we expected to receive under the 2017 ASR Agreement.  During the nine months ended September 30, 2018, we received an additional 13,657 shares of our common stock from BofA, representing the final settlement of the 2017 ASR Agreement.  We purchased a total of 1,521,100 shares of our common stock under the 2017 ASR Agreement at an average price per share of $65.74.  Subsequent to the completion of the 2017 ASR Agreement, we purchased an additional 142,780 shares of our common stock at an average price per share of $66.49 under the 2017 Repurchase Program.