Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected quarterly financial data and earnings per share [Abstract]
Revenues	$ 849,736us-gaap_Revenues	$ 1,173,970us-gaap_Revenues	$ 1,159,931us-gaap_Revenues	$ 949,189us-gaap_Revenues	$ 968,096us-gaap_Revenues	$ 1,060,340us-gaap_Revenues	$ 965,098us-gaap_Revenues	$ 952,435us-gaap_Revenues	$ 4,132,826us-gaap_Revenues	$ 3,945,969us-gaap_Revenues	$ 3,376,085us-gaap_Revenues
Earnings from continuing operations	(6,974)	3,855	3,975	5,363	289	7,238	6,521	8,073	6,219	22,121	27,472
Earnings from continuing operations, Per Share (in dollars per share)	$ (1.65)	$ 0.92	$ 0.94	$ 1.27	$ 0.06	$ 1.72	$ 1.55	$ 1.91	$ 1.48	$ 5.24	$ 6.51
Net Earnings (Loss), Amount	(6,670)us-gaap_NetIncomeLoss	3,855us-gaap_NetIncomeLoss	3,975us-gaap_NetIncomeLoss	5,363us-gaap_NetIncomeLoss	109us-gaap_NetIncomeLoss	7,156us-gaap_NetIncomeLoss	6,330us-gaap_NetIncomeLoss	8,015us-gaap_NetIncomeLoss	6,523us-gaap_NetIncomeLoss	21,610us-gaap_NetIncomeLoss	27,791us-gaap_NetIncomeLoss
Net Earnings (Loss), Per Share (in dollars per share)	$ (1.58)us-gaap_EarningsPerShareBasicAndDiluted	$ 0.92us-gaap_EarningsPerShareBasicAndDiluted	$ 0.94us-gaap_EarningsPerShareBasicAndDiluted	$ 1.27us-gaap_EarningsPerShareBasicAndDiluted	$ 0.02us-gaap_EarningsPerShareBasicAndDiluted	$ 1.70us-gaap_EarningsPerShareBasicAndDiluted	$ 1.50us-gaap_EarningsPerShareBasicAndDiluted	$ 1.90us-gaap_EarningsPerShareBasicAndDiluted	$ 1.55us-gaap_EarningsPerShareBasicAndDiluted	$ 5.12us-gaap_EarningsPerShareBasicAndDiluted	$ 6.59us-gaap_EarningsPerShareBasicAndDiluted
Dividends	$ 927us-gaap_PaymentsOfDividends	$ 928us-gaap_PaymentsOfDividends	$ 928us-gaap_PaymentsOfDividends	$ 928us-gaap_PaymentsOfDividends	$ 928us-gaap_PaymentsOfDividends	$ 927us-gaap_PaymentsOfDividends	$ 928us-gaap_PaymentsOfDividends	$ 0us-gaap_PaymentsOfDividends	$ 3,711us-gaap_PaymentsOfDividends	$ 2,783us-gaap_PaymentsOfDividends	$ 2,615us-gaap_PaymentsOfDividends
Dividends, Per share (in dollars per share)	$ 0.22	$ 0.22	$ 0.22	$ 0.22	$ 0.22	$ 0.22	$ 0.22	$ 0	$ 0.88	$ 0.66

Aggregate dividends paid during the period for each share of common stock outstanding.

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Amount of income (loss) from continuing operations attributable to the parent. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests.

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The amount of net income (loss) from continuing operations per each basic and diluted share of common stock or unit when the per share amount is the same for both basic and diluted shares.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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