Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Stock-based Compensation [Abstract]

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

Non-vested restricted share awards outstanding under both the Plan and the Director Plan as of December 31, 2017 and changes during the year were as follows:

	Number of Shares		Weighted Average Grant Date Fair Value per Share
Non-vested at December 31, 2016	545,614		$	110.11
Granted	203,512		101.97
Vested	(191,022	)	114.11
Forfeited	(21,354	)	114.89
Non-vested at December 31, 2017	536,750		$	105.42

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

For the years ended December 31, 2017, 2016 and 2015, stock-based compensation expense under both the Plan and the Director Plan recognized in the income statement is as follows (in thousands):

	2017		2016		2015
Cost of product sales and services	$	8,879	$	10,073	$	10,126
General and administrative	14,063		12,006		11,153
Total stock-based compensation expense	$	22,942	$	22,079	$	21,279