Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Statement of Income and Comprehensive Income [Abstract]
Net income (loss), Before-tax Amount	$ 37,347		$ (43,764)		$ 73,262		$ (123,628)
Net income (loss), Tax (Expense) Benefit	2,105		4,764		2,182		5,220
Net income (loss), Net of Tax Amount	39,452		(39,000)		75,444		(118,408)
Net unrealized gains/losses on cash flow hedges: Before-tax Amount
Net unrealized gains (losses) arising during the period, Before-tax Amount	(420)		(3,069)		(1,555)		(6,974)
Valuation allowance for the change in deferred taxes arising from unrealized gains/losses, Before-tax Amount	0	[1]	0	[1]	0	[1]	0	[1]
Net unrealized gains (losses), Before-tax Amount	(420)		(3,069)		(1,555)		(6,974)
Net unrealized gains/losses on cash flow hedges: Tax (Expense) Benefit
Net unrealized gains (losses) arising during the period, Tax (Expense) Benefit	171		1,305		608		2,614
Valuation allowance for the change in deferred taxes arising from unrealized gains/losses, Tax (Expense) Benefit	(171)	[1]	1,309	[1]	(608)	[1]	0	[1]
Net unrealized gains (losses), Tax (Expense) Benefit	0		2,614		0		2,614
Net unrealized gains/losses on cash flow hedges: Net of Tax Amount
Net unrealized gains (losses) arising during the period, Net of Tax Amount	(249)		(1,764)		(947)		(4,360)
Valuation allowance for the change in deferred taxes arising from unrealized gains/losses, Net of Tax Amount	(171)	[1]	1,309	[1]	(608)	[1]	0	[1]
Net unrealized gains (losses), Net of Tax Amount	(420)		(455)		(1,555)		(4,360)
Net unrealized gains/losses on investment securities available for sale: Before-tax Amount
Net unrealized gains (losses) arising during the period, Before-tax Amount	13,146		34,146		11,076		22,462
Reclassification adjustment for (gains) losses realized in net income, Tax (Expense) Benefit	(4,170)		(377)		(24,253)		(1,797)
Valuation allowance for the change in deferred taxes arising from unrealized gains/losses, Before-tax Amount	0		0		0		0
Net unrealized gains (losses), Before-tax Amount	8,976		33,769		(13,177)		20,665
Net unrealized gains/losses on investment securities available for sale: Tax (Expense) Benefit
Net unrealized gains (losses) arising during the period, Tax (Expense) Benefit	(5,062)		(12,799)		(4,263)		(8,250)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Tax	1,605		145		9,338		692
Valuation allowance for the change in deferred taxes arising from unrealized gains/losses, Tax (Expense) Benefit	3,457		5,096		(5,075)		0
Net unrealized gains (losses), Tax (Expense) Benefit	0		(7,558)		0		(7,558)
Net unrealized gains/losses on investment securities available for sale: Net of Tax Amount
Net unrealized gains (losses) arising during the period, Net of Tax Amount	8,084		21,347		6,813		14,212
Reclassification adjustment for (gains) losses realized in net income, Net of Tax Amount	(2,565)		(232)		(14,915)		(1,105)
Valuation allowance for the change in deferred taxes arising from unrealized gains/losses, Net of Tax Amount	3,457		5,096		(5,075)		0
Net unrealized gains (losses), Net of Tax Amount	8,976		26,211		(13,177)		13,107
Amortization of post-retirement unfunded health benefit: Before-tax Amount
Amortization arising during the period, Before-tax Amount	642		0		642		0
Valuation allowance for the change in deferred taxes arising from amortization, Before-tax Amount	0		0		0		0
Net amortization, Before-tax Amount	642		0		642		0
Amortization of post-retirement unfunded health benefit: Tax (Expense) Benefit
Amortization arising during the period, Tax (Expense) Benefit	(247)		0		(247)		0
Valuation allowance for the change in deferred taxes arising from amortization, Tax (Expense) Benefit	247		0		247		0
Net amortization, Tax (Expense) Benefit	0		0		0		0
Amortization of post-retirement unfunded health benefit: Net of Tax Amount
Amortization arising during the period, Net of Tax Amount	395		0		395		0
Valuation allowance for the change in deferred taxes arising from amortization, Net of Tax Amount	247		0		247		0
Net amortization, Net of Tax Amount	642		0		642		0
Other comprehensive income (loss), Before-tax Amount	9,198		30,700		(14,090)		13,691
Less: comprehensive loss attributable to non-controlling interest, Before-tax Amount	0		0		0		(220)
Comprehensive income (loss), Before-tax Amount	46,545		(13,064)		59,172		(109,717)
Other comprehensive income (loss), Tax (Expense) Benefit	0		4,944		0		4,944
Less: comprehensive loss attributable to non-controlling interest, Tax (Expense) Benefit	0		0		0		0
Comprehensive income (loss), Tax (Expense) Benefit	2,105		(180)		2,182		276
Other comprehensive income (loss), Net of Tax Amount	9,198		25,756		(14,090)		8,747
Less: comprehensive loss attributable to non-controlling interest, Net of Tax Amount	0		0		0		(220)
Comprehensive income (loss), Net of Tax Amount	$ 48,650		$ (13,244)		$ 61,354		$ (109,441)

[1] In accordance with ASC 740-20-45-11(b), the deferred tax asset valuation allowance associated with unrealized gains and losses not recognized in income is charged directly to other comprehensive income (loss).