Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2015

Equity [Abstract]

Summary of Activities in Common Stock

The following table details activity in our common stock:

	Years ended December 31,
	2015						2014						2013
	Shares			Amount			Shares			Amount			Shares		Amount
Stock option exercises		1,118		$	23,160			855		$	14,680			1,443	$	18,289
Purchases of common stock		(5	)		(645	)		(294	)		(22,817	)		—		—
Employee stock plan purchases		43			4,671			53			4,144			64		3,542
Shares issued for acquisitions		2,149			364,333			17			1,473			—		—