Goodwill and Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2009	Dec. 31, 2010
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	$ 10,219		$ 13,803
Finite-Lived Intangible Assets-Future Amortization Expense [Abstract]
2012	2,200
2013	1,546
2014	766
2015	726
2016	582
Thereafter	4,399
Expected net total amortization expense for intangible assets	10,219
Goodwill [Line Items]
Goodwill, gross	335,829		335,829
Accumulated Impairment	(228)		(228)
Goodwill	335,601		335,601
Impairment charge		228
Commercial [Member]
Goodwill [Line Items]
Goodwill, gross	266,728		266,728
Accumulated Impairment	0		0
Goodwill	266,728		266,728
Consumer [Member]
Goodwill [Line Items]
Goodwill, gross	39,251		39,251
Accumulated Impairment	(228)		(228)
Goodwill	39,023		39,023
Wealth Management [Member]
Goodwill [Line Items]
Goodwill, gross	29,850		29,850
Accumulated Impairment	0		0
Goodwill	29,850		29,850
TEXAS [Member]
Goodwill [Line Items]
Goodwill	240,122		240,122
OKLAHOMA [Member]
Goodwill [Line Items]
Goodwill	8,173		8,173
COLORADO [Member]
Goodwill [Line Items]
Goodwill	55,611		55,611
ARIZONA [Member]
Goodwill [Line Items]
Goodwill	16,422		16,422
NEW MEXICO [Member]
Goodwill [Line Items]
Goodwill	15,273		15,273
Core Deposits Premiums [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	109,417		109,417
Accumulated amortization	107,023		104,795
Finite-lived intangible assets, net	2,394		4,622
Finite-Lived Intangible Assets-Future Amortization Expense [Abstract]
2012	815
2013	485
2014	432
2015	392
2016	248
Thereafter	22
Expected net total amortization expense for intangible assets	2,394
Core Deposits Premiums [Member] | TEXAS [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	1,817		3,408
Core Deposits Premiums [Member] | COLORADO [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	548		1,058
Core Deposits Premiums [Member] | ARIZONA [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	29		156
Other Identifiable Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	17,291		17,291
Accumulated amortization	9,466		8,110
Finite-lived intangible assets, net	7,825		9,181
Finite-Lived Intangible Assets-Future Amortization Expense [Abstract]
2012	1,385
2013	1,061
2014	334
2015	334
2016	334
Thereafter	4,377
Expected net total amortization expense for intangible assets	7,825
Other Identifiable Intangible Assets [Member] | Kansas/Missouri [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	790		790
Other Identifiable Intangible Assets [Member] | OKLAHOMA [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	5,548		6,048
Other Identifiable Intangible Assets [Member] | COLORADO [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	$ 1,487		$ 2,343