Stockholders' Equity (Changes in Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Unrealized gains on investment securities available for sale:
Net unrealized holding gain (loss) arising during the period, Before Tax	$ (18,774)	$ 13,052	$ 4,375	$ 34,887
Amounts reclassified to gain on investment securities available for sale, net, Before Tax	(1,128)	0	(3,150)	(361)
Net change in unrealized gains on securities available for sale, Before Tax	(19,902)	13,052	1,225	34,526
Net unrealized holding gain (loss) arising during the period, Tax Effect	7,632	(5,030)	(2,530)	(13,454)
Amounts reclassified to gain on investment securities available for sale, net, Tax Effect	445	0	1,244	139
Net change in unrealized gains on securities available for sale, Tax Effect	8,077	(5,030)	(1,286)	(13,315)
Net unrealized holding gain (loss) arising during the period, Net of Tax	(11,142)	8,022	1,845	21,433
Amounts reclassified to gain on investment securities available for sale, net, Net of Tax	(683)	0	(1,906)	(222)
Net change in unrealized gains on securities available for sale	(11,825)	8,022	(61)	21,211
Unrealized losses on derivative instruments:
Net unrealized holding gain (loss) arising during the period, Before Tax	15,136	(12,924)	(5,551)	(20,374)
Amounts reclassified to interest expense on deposits, Before Tax	1,433	1,412	2,853	2,807
Amounts reclassified to interest expense on borrowings, Before Tax	5,098	5,246	10,221	10,400
Net change in unrealized losses on derivative instruments, Before Tax	21,667	(6,266)	7,523	(7,167)
Net unrealized holding gain (loss) arising during the period, Tax Effect	(5,496)	4,985	2,484	7,859
Amounts reclassified to interest expense on deposits, Tax Effect	(579)	(545)	(1,127)	(1,083)
Amounts reclassified to interest expense on borrowings, Tax Effect	(2,061)	(2,024)	(4,037)	(4,012)
Net change in unrealized losses on derivative instruments, Tax Effect	(8,136)	2,416	(2,680)	2,764
Net unrealized holding gain (loss) arising during the period, Net of Tax	9,640	(7,939)	(3,067)	(12,515)
Amounts reclassified to interest expense on deposits, Net of Tax	854	867	1,726	1,724
Amounts reclassified to interest expense on borrowings, Net of Tax	3,037	3,222	6,184	6,388
Net change in unrealized losses on derivative instruments	13,531	(3,850)	4,843	(4,403)
Other comprehensive income (loss), Before Tax	1,765	6,786	8,748	27,359
Other comprehensive income (loss), Tax Effect	(59)	(2,614)	(3,966)	(10,551)
Other comprehensive income (loss)	$ 1,706	$ 4,172	$ 4,782	$ 16,808