Shareholders' Equity (Tables)

9 Months Ended

Sep. 30, 2016

Equity [Abstract]

Summary of Activities in Common Stock

The following table details activity in our common stock:

	Nine Months ended September 30,
	2016						2015
	Shares			Amount			Shares			Amount
Purchases of common stock		(758	)	$	(94,499	)		(5	)	$	(645	)
Stock option exercises		564			15,089			420			8,369
Employee stock plan purchases		34			4,429			33			3,367
Shares issued for acquisition		—			—			13			1,519