Consolidated Statement of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Tax on unrealized holding gain/(loss) on investments arising during period	$ (14)	$ (1)	$ 114
Tax on reclassification adjustments for gain on investments included in net income	22	23	25
Tax on unrealized gain on derivatives arising during the period	0	0	45
Tax on reclassification adjustments for gain on derivatives included in net income	$ 0	$ 0	$ 45