Income Taxes (Sources of Income) (Details) (USD $) In Thousands, 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
Income Before Income Tax Domestic And Foreign [Line Items]
Income before income taxes	$ 136,732	$ 32,447	$ 158,058	$ 193,545	$ 141,355	$ 127,814	$ (5,934)	$ 164,425	$ 520,782	$ 427,660	$ 511,447
Non-U.S.
Income Before Income Tax Domestic And Foreign [Line Items]
Income before income taxes									447,875	401,778	474,412
United States
Income Before Income Tax Domestic And Foreign [Line Items]
Income before income taxes									$ 72,907	$ 25,882	$ 37,035