Securities (Available for sale securities losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value
Less than 12 months	$ 519,935	$ 821,737
12 months or longer	144,530	147,022
Total	664,465	968,759
Unrealized Losses
Less than 12 months	(14,612)	(16,566)
12 months or longer	(4,561)	(5,552)
Total	(19,173)	(22,118)
Total debt securities
Fair Value
Less than 12 months	519,935	815,171
12 months or longer	144,530	147,022
Total	664,465	962,193
Unrealized Losses
Less than 12 months	(14,612)	(16,522)
12 months or longer	(4,561)	(5,552)
Total	(19,173)	(22,074)
U.S. government corporations and agencies
Fair Value
Less than 12 months	0	22,359
12 months or longer	0	0
Total	0	22,359
Unrealized Losses
Less than 12 months	0	(103)
12 months or longer	0	0
Total	0	(103)
Mortgage-backed securities
Fair Value
Less than 12 months	517,699	724,330
12 months or longer	144,275	139,562
Total	661,974	863,892
Unrealized Losses
Less than 12 months	(14,569)	(15,523)
12 months or longer	(4,560)	(5,361)
Total	(19,129)	(20,884)
Obligations of states and political subdivisions
Fair Value
Less than 12 months	2,236	68,482
12 months or longer	255	7,460
Total	2,491	75,942
Unrealized Losses
Less than 12 months	(43)	(896)
12 months or longer	(1)	(191)
Total	(44)	(1,087)
Corporate debt securities
Fair Value
Less than 12 months	0	0
12 months or longer	0	0
Total	0	0
Unrealized Losses
Less than 12 months	0	0
12 months or longer	0	0
Total	0	0
Equity securities
Fair Value
Less than 12 months	0	6,566
12 months or longer	0	0
Total	0	6,566
Unrealized Losses
Less than 12 months	0	(44)
12 months or longer	0	0
Total	$ 0	$ (44)