Derivatives Notional Amounts (Details) (USD $)	3 Months Ended																								12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended
	Mar. 31, 2011 Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member] CHF / GBP [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member] CHF / GBP [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member] EUR / NZD [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member] EUR / NZD [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member] AUD / NZD [Member]	Mar. 31, 2011 Foreign Exchange Forward [Member] Not Designated as Hedging Instrument [Member] AUD / NZD [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / AUD [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / AUD [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / CAD [Member] [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / CAD [Member] [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / CHF [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / CHF [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / GBP [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / GBP [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / SEK [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / SEK [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / NOK [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / NOK [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / NZD [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] EUR / NZD [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] GBP / CHF [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] GBP / CHF [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] GBP / SEK [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] GBP / SEK [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] CHF / SEK [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] CHF / SEK [Member]	Mar. 31, 2012 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] NOK / CHF [Member]	Dec. 31, 2011 Foreign Exchange Forward [Member] Designated as Hedging Instrument [Member] NOK / CHF [Member]	Mar. 31, 2012 Minimum [Member]	Mar. 31, 2012 Maximum [Member]
Derivative [Line Items]
Derivative, Percentage of Forcasted Transactions With Currency Rate Exposure																																																																60.00%	90.00%
Notional Amount of Derivatives, Matured During Period		$ 36,967,000	$ 39,381,000
Notional Amount				23,516,000	29,651,000	7,138,000	17,131,000	1,377,000	0	0	7,107,000	0	145,000	3,315,000	0	8,137,000	0	0	5,268,000	2,483,000	0	1,066,000	0	136,362,000	124,945,000	2,559,000	3,324,000	21,482,000	8,424,000	6,870,000	8,130,000	41,014,000	42,267,000	1,396,000	1,806,000	6,192,000	8,256,000	9,974,000	4,520,000	9,298,000	14,029,000	866,000	1,220,000	1,896,000	0	4,084,000	5,433,000	17,148,000	17,201,000	1,503,000	0	1,327,000	0	5,837,000	7,009,000	731,000	929,000	3,166,000	1,690,000	318,000	271,000	701,000	436,000
Unrealized Gain (Loss)																								2,147,000	1,244,000	26,000	104,000	125,000	29,000	3,000	(16,000)	576,000	701,000	(6,000)	19,000	204,000	86,000	149,000	19,000	776,000	(146,000)	(27,000)	(48,000)	9,000	0	42,000	(22,000)	(262,000)	9,000	(11,000)	0	(12,000)	0	526,000	505,000	(11,000)	(5,000)	64,000	12,000	(9,000)	(2,000)	(15,000)	(1,000)
Gain (Loss)	$ 6,000	$ 83,000	$ 817,000	$ 83,000	$ 823,000	$ 77,000	$ 404,000	$ 7,000	$ 0	$ 0	$ 256,000	$ 0	$ 6,000	$ 63,000	$ 0	$ (73,000)	$ 0	$ 0	$ 157,000	$ (2,000)	$ 0	$ 11,000	$ 0