Shareholders' Equity Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Attributable to Parent [Abstract]

Schedule of Share Repurchases [Table Text Block]

The following table sets forth share repurchase information for the periods indicated:

	Year Ended December 31,
	2015			2014
Total number of shares repurchased	1,396,693			795,321
Average price paid per share	$	76.78		$	78.61
Total value of shares repurchased	$	107.2	million	$	62.5	million