Earnings Per Share - EPS Reconciliation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share Reconciliation
Basic EPS - net income	$ 126,673	$ 114,920	$ 103,637
Basic EPS - shares	40,446	38,065	38,384
Basic EPS - per share amount	$ 3.13	$ 3.02	$ 2.70
Dilutive effect of 2.875% convertible debt - net income	780	1,819	1,808
Dilutive effect of 2.875% convertible debt - shares	1,287	3,033	3,033
Dilutive effect of 2.875% convertible debt - per share amount	$ (0.08)	$ (0.18)	$ (0.15)
Dilutive effect of stock options, restricted stock units, and shares issuable to Philips - net income	0	0	0
Dilutive effect of stock options, restricted stock units, and shares issuable to Philips - shares	662	630	630
Dilutive effect of stock options, restricted stock units, and shares issuable to Philips - per share amount	$ (0.04)	$ (0.04)	$ (0.04)
Diluted EPS - net income	$ 127,453	$ 116,739	$ 105,445
Diluted EPS - shares	42,395	41,728	42,047
Diluted EPS - per share amount	$ 3.01	$ 2.80	$ 2.51