Fair Value Measurements Fair Value Recurring Basis (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Dec. 31, 2012 Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Not Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Dec. 31, 2012 Not Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Not Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Dec. 31, 2012 Not Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Mar. 31, 2013 US Government and Government Agencies and Authorities [Member]	Dec. 31, 2012 US Government and Government Agencies and Authorities [Member]	Mar. 31, 2013 US Government-sponsored Enterprises Debt Securities [Member]	Dec. 31, 2012 US Government-sponsored Enterprises Debt Securities [Member]	Mar. 31, 2013 Municipal Bonds [Member]	Dec. 31, 2012 Municipal Bonds [Member]	Mar. 31, 2013 Mortgage Backed Securities, Other [Member]	Dec. 31, 2012 Mortgage Backed Securities, Other [Member]	Mar. 31, 2013 Other Aggregated Investments [Member]	Dec. 31, 2012 Other Aggregated Investments [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member] Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member] Not Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Not Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member] Not Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Not Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member] US Government and Government Agencies and Authorities [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] US Government and Government Agencies and Authorities [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member] US Government-sponsored Enterprises Debt Securities [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] US Government-sponsored Enterprises Debt Securities [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member] Municipal Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Municipal Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Mortgage Backed Securities, Other [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 1 [Member] Mortgage Backed Securities, Other [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 1 [Member] Other Aggregated Investments [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Other Aggregated Investments [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Not Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Not Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Not Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Not Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] US Government and Government Agencies and Authorities [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] US Government and Government Agencies and Authorities [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] US Government-sponsored Enterprises Debt Securities [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] US Government-sponsored Enterprises Debt Securities [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Municipal Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Municipal Bonds [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Mortgage Backed Securities, Other [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Mortgage Backed Securities, Other [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Other Aggregated Investments [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Other Aggregated Investments [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Not Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Not Designated as Hedging Instrument [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Not Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Not Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] US Government and Government Agencies and Authorities [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] US Government and Government Agencies and Authorities [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] US Government-sponsored Enterprises Debt Securities [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] US Government-sponsored Enterprises Debt Securities [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Municipal Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Municipal Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Mortgage Backed Securities, Other [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Mortgage Backed Securities, Other [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Other Aggregated Investments [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Other Aggregated Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	$ 736,610	$ 699,300							$ 2,414	$ 2,753	$ 200,253	$ 155,002	$ 207,654	$ 210,984	$ 314,416	$ 317,927	$ 11,873	$ 12,634	$ 11,873	$ 12,634							$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 11,873	$ 12,634	$ 724,737	$ 686,666							$ 2,414	$ 2,753	$ 200,253	$ 155,002	$ 207,654	$ 210,984	$ 314,416	$ 317,927	$ 0	$ 0	$ 0	$ 0							$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Derivative Assets					2,664	2,915																	0	0																	2,664	2,915																	0	0
Foreign Currency Contract, Asset, Fair Value Disclosure							216	120																	0	0																	216	120																	0	0
Alternative Investments, Fair Value Disclosure	6,010	5,892																	5,324	5,206																	686	686																	0	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure			$ 4,750	$ 5,189	$ 2,746	$ 3,047	$ 216	$ 120													$ 0	$ 0	$ 0	$ 0	$ 0	$ 0													$ 4,750	$ 5,189	$ 2,746	$ 3,047	$ 216	$ 120													$ 0	$ 0	$ 0	$ 0	$ 0	$ 0

This element represents the total fair market value of investments in certain entities that calculate net asset value per share (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments). This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements, but may also be used in both the balance sheet and disclosure in the same submission. This item represents alternative investments as of the balance sheet date which may include investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds, and any other investment in which investee management calculates net asset value per share as the primary metric for investment value.

+ References+ Details

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References+ Details

- Definition

Derivative instrument obligations meeting the definition of a liability which the Company is a party to as of the balance sheet date.

+ References+ Details