Supplemental Cash Flow Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Supplemental disclosure:
Interest paid	$ 0	$ 1	$ 0	$ 1
Income taxes paid	7,864	8,915	18,397	15,004
Non-cash investing and financing activities:
Non-cash capital expenditures	$ (149)	$ (265)	$ 115	$ 25