Recent Accounting Pronouncements (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Jan. 01, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total expenses	$ 568,356,000	$ 694,535,000
Operating income	69,506,000	89,214,000
Income taxes	19,979,000	25,721,000
Net income for common stock	31,866,000	45,787,000
Other	481,531,000		542,523,000
Liabilities and Equity	11,273,447,000		11,185,142,000
Deferred Income Tax Liabilities And Other Liabilities			633,570,000
Liabilities	9,341,245,000		9,360,276,000
Retained earnings	296,680,000		296,654,000	255,030,000
Common stock equity	1,897,909,000	1,745,124,000	1,790,573,000	1,726,406,000
American Savings Bank (ASB)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					700,000
Amortization Method Qualified Affordable Housing Project Investments, Amortization	1,300,000
Affordable Housing Tax Credit, Amount	1,400,000
Affordable Housing Tax Credit, Other Tax Benefits, Amount	500,000
Income taxes	7,156,000	8,133,000
Net income for common stock		14,399,000
Other	305,917,000		305,416,000
Liabilities and Equity			5,566,222,000
Deferred Income Tax Liabilities And Other Liabilities			118,363,000
Liabilities	5,181,271,000		5,032,434,000
Retained earnings	217,909,000		211,934,000
Common stock equity	543,606,000		533,788,000
Scenario, Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income taxes		24,673,000
Net income for common stock		45,927,000
Other			541,542,000
Liabilities and Equity			11,184,161,000
Deferred Income Tax Liabilities And Other Liabilities			631,734,000
Liabilities			9,358,440,000
Retained earnings			297,509,000	255,694,000
Common stock equity			1,791,428,000	1,727,070,000
Scenario, Previously Reported | American Savings Bank (ASB)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income taxes		7,085,000
Net income for common stock		14,539,000
Other			304,435,000
Liabilities and Equity			5,565,241,000
Deferred Income Tax Liabilities And Other Liabilities			116,527,000
Liabilities			5,030,598,000
Retained earnings			212,789,000
Common stock equity			534,643,000
Accounting Standards Update 2014-01 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income taxes		1,048,000
Net income for common stock		(140,000)
Other			981,000
Liabilities and Equity			981,000
Deferred Income Tax Liabilities And Other Liabilities			1,836,000
Liabilities			1,836,000
Retained earnings			(855,000)	(664,000)
Common stock equity			(855,000)	(664,000)
Accounting Standards Update 2014-01 | Restatement Adjustment | American Savings Bank (ASB)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income taxes		1,048,000
Net income for common stock		(140,000)
Other			981,000
Liabilities and Equity			981,000
Deferred Income Tax Liabilities And Other Liabilities			1,836,000
Liabilities			1,836,000
Retained earnings			(855,000)
Common stock equity			(855,000)
Bank
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total expenses	43,717,000	41,088,000
Operating income	20,631,000	22,531,000
Income taxes	7,156,000	8,133,000
Net income for common stock	13,475,000	14,399,000
Bank | American Savings Bank (ASB)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total expenses		37,462,000
Operating income		22,532,000
Liabilities and Equity	5,724,877,000		5,566,222,000
Bank | Scenario, Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total expenses		41,996,000
Operating income		21,623,000
Bank | Scenario, Previously Reported | American Savings Bank (ASB)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total expenses		38,370,000
Operating income		21,624,000
Bank | Accounting Standards Update 2014-01 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total expenses		(908,000)
Operating income		908,000
Bank | Accounting Standards Update 2014-01 | Restatement Adjustment | American Savings Bank (ASB)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total expenses		(908,000)
Operating income		$ 908,000