Goodwill and Intangible Assets Goodwill (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Goodwill [Roll Forward]
Balance at beginning of year	$ 535,518,000	$ 534,862,000	$ 534,385,000
Other goodwill additions, net	487,000	656,000	477,000
Balance at end of year	536,005,000	535,518,000	534,862,000
Goodwill	536,005,000	535,518,000	534,862,000
Subsidiaries [Member] | The Bank [Member]
Goodwill [Roll Forward]
Balance at end of year		97,400,000
Goodwill Impairment Test Adjusted Net Book Value Exceeding Fair Value Amount	82,000,000	64,000,000
Goodwill Impairment Test Adjusted Net Book Value Exceeding Fair Value Percent	31.00%	24.00%
Goodwill		97,400,000
Subsidiaries [Member] | Columbia Bank [Member]
Goodwill [Roll Forward]
Balance at end of year		112,600,000
Goodwill Impairment Test Adjusted Net Book Value Exceeding Fair Value Amount	84,000,000	78,000,000	37,000,000
Goodwill Impairment Test Adjusted Net Book Value Exceeding Fair Value Percent	28.00%	26.00%	14.00%
Goodwill		112,600,000
Subsidiaries [Member] | Three Reporting Units [Member]
Goodwill [Roll Forward]
Balance at beginning of year	77,600,000
Number Of Reporting Units	3
Goodwill Impairment Test Fair Value Exceeding Adjusted Net Book Value Percent		5.00%
Subsidiaries [Member] | Other Reporting Units [Member]
Goodwill [Roll Forward]
Balance at end of year		248,400,000
Goodwill		$ 248,400,000
Goodwill Impairment Test Fair Value Exceeding Adjusted Net Book Value Percent		18.00%