Summary of Derivative Financial Instruments Notional Amounts on Outstanding Positions (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Foreign currency exchange forward contracts by currency:
Total notional value, net	$ 143,116	$ 50,400
Latest maturity date	Dec. 01, 2015	Dec. 01, 2012
Japanese Yen [Member]
Foreign currency exchange forward contracts by currency:
Total notional value, net	112,500	27,500
Euro [Member]
Foreign currency exchange forward contracts by currency:
Total notional value, net	5,159	10,055
Australian Dollar [Member]
Foreign currency exchange forward contracts by currency:
Total notional value, net	4,178
Mexican Peso [Member]
Foreign currency exchange forward contracts by currency:
Total notional value, net	11,400	6,500
Pound Sterling [Member]
Foreign currency exchange forward contracts by currency:
Total notional value, net	8,742	6,345
New Zealand Dollar [Member]
Foreign currency exchange forward contracts by currency:
Total notional value, net	$ 1,137