Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Summary of Activities in Common Stock

The following table details activity in our common stock:

	Years ended December 31,
	2014						2013				2012
	Shares			Amount			Shares		Amount		Shares		Amount
Stock option exercises		855		$	14,680			1,443	$	18,289		1,218	$	12,443
Purchases of common stock		(294	)		(22,817	)		—		—		—		—
Employee stock plan purchases		53			4,144			64		3,542		81		2,641
Shares issued for acquisition		17			1,473			—		—		60		2,815