Parent Company Information (Components of Condensed Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on available for sale securities	$ (9,069)	$ (22,828)	$ 19,038
Net unrealized gains (losses) on derivative instruments	825	(3,136)	(12,506)
Other comprehensive loss of subsidiaries and associated companies	208,240	182,884	192,014
Other comprehensive income (loss), net of tax	1,113	(21,845)	(7,712)
Parent Company [Member]
Condensed Statement of Income Captions [Line Items]
Net income	207,127	204,729	199,726
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on available for sale securities	584	(2,109)	725
Net unrealized gains (losses) on derivative instruments	1,223	1,223	(2,932)
Other comprehensive loss of subsidiaries and associated companies	(694)	(20,959)	(5,505)
Other comprehensive income (loss), net of tax	1,113	(21,845)	(7,712)
Comprehensive income	$ 208,240	$ 182,884	$ 192,014